Progress report for FW24-021
Project Information
This research project focuses on evaluating crop sustainability within a cold-water aquaponics system using a deep-water methodology. The primary objective is to establish the feasibility of plant cultivation in this system without the necessity of external heating. This is achieved through the utilization of cold-resistant plants and bacteria.
The project's success will be measured by assessing the volume of produce cultivated and sold in local markets and food hubs, with the project's financial viability determined by analyzing the net profit margin at the end of the season.
Additionally, the research incorporates a control aquaponics bed to provide a comparative basis for the evaluation.
By showcasing the potential of aquaponics systems and seasonal crop cultivation in the state of Washington, this project offers a resource-efficient and cost-effective alternative for individuals interested in adopting aquaponic farming practices. This approach eliminates the need for costly heating systems. Furthermore, the project serves as an educational platform, emphasizing the adaptability of aquaponic systems throughout different seasons.
Dissemination of the project's findings will occur through various channels, including workshops, article publications, lectures, and online platforms, enabling broad outreach and awareness. This comprehensive approach ensures effective communication of the project's message, fostering understanding and engagement among diverse audiences.
The central objective of this project revolves around assessing the feasibility of cultivating crops in a cold-water aquaponics system, utilizing a deep-water methodology to ensure long-term sustainability. To gauge the effectiveness of this approach, we will closely monitor the quantity of crops sold in local markets and neighboring food hubs, with a keen focus on evaluating its financial viability, measured through the net profit margin at the season's conclusion. We will also be implementing a heated system as a control for comparative analysis.
Through this initiative, we aim to underscore the considerable potential of aquaponics within the state of Washington. Our intent is to highlight the array of seasonal produce that can be successfully cultivated without the necessity of expensive heating systems. We aspire to provide an alternative perspective on sustainable farming, offering a model that can inspire and guide others within the agricultural community.
Furthermore, this project carries significant educational value. By showcasing a sustainable aquaponics system that aligns with the constraints of seasonal growth, we aim to facilitate knowledge dissemination and encourage the adoption of environmentally friendly practices within the broader aquaponics community.
Month 1: Set up the non-heated aquaponic system and develop educational materials.
Month 2: Introduce cold-resistant plant varieties and conduct the first workshop on non-heated aquaponics.
Month 3: Monitor plant growth and water quality, and organize a field day to showcase the system.
Month 4: Assess plant productivity and release the first video tutorial on non-heated aquaponics.
Month 5: Analyze water quality and offer personalized consultations to interested producers.
Month 6: Perform a cost-benefit analysis and conduct a webinar addressing FAQs.
Month 7: Summarize research findings and publish articles in local agricultural publications.
Month 8: Release the final video showcasing project success and prepare for presentations.
Month 9: Present project findings at a workshop or conference.
This timeline provides an overview of the major activities and milestones for each month of the project, aligning with the research and educational objectives.
Cooperators
- - Technical Advisor
Research
Research Design, Methods, and Findings
This project investigates the feasibility, performance, and economic viability of non-heated, deep-water aquaponics systems for cold-climate food production. The research was structured as a multi-year effort. Year One focused on system establishment, baseline observations, and identifying key performance patterns across seasons. Year Two built on those findings through validation, refinement, and comparative analysis of seasonal crop production, water quality dynamics, and management strategies.
Year One: System Establishment and Baseline Findings
Objective 1: Evaluate the growth and productivity of cold-resistant plant varieties in a non-heated aquaponic system
Methods and Materials:
A range of cold-resistant plant species suitable for aquaponic cultivation were selected and grown within a deep-water aquaponic system. Replicated production areas were established to monitor plant growth parameters, including plant vigor, leaf development, root structure, and harvestable biomass. Crop productivity was assessed through yields of marketable produce across seasonal planting cycles.
Objective 2: Assess the performance and stability of the deep-water aquaponic system in maintaining water quality parameters
Methods and Materials:
Sensors and monitoring equipment were used to track water temperature, pH, dissolved oxygen, ammonia, and nitrate levels. Manual water sampling was conducted regularly to verify sensor readings and observe seasonal trends in nutrient cycling and water quality stability.
Objective 3: Determine the economic viability of non-heated aquaponics through cost-benefit analysis
Methods and Materials:
Costs associated with system setup, operation, and maintenance were documented, including infrastructure, fish feed, seeds or seedlings, labor, and utilities. Harvested produce was tracked and assigned market value based on local sales through farmers markets and food hub outlets. A preliminary cost-benefit analysis was conducted to compare production output with operating costs.
Year One Findings
Year One established that non-heated, deep-water aquaponics systems can function effectively in a temperate climate. Slow-moving water buffered root zones against freezing temperatures, supporting continued plant growth during colder months. Dissolved oxygen levels were consistently higher during winter than during summer, contributing to strong root health and plant vigor.
Seasonal production patterns were observed, with strong winter and early spring performance and reduced output during warmer periods. These findings confirmed the technical feasibility of non-heated aquaponics while identifying temperature- and oxygen-related challenges for summer production. Year One also established the importance of seasonal management in passive systems and provided the baseline observations that guided subsequent refinements in Year Two.
Year Two: Validation, Refinement, and Comparative Findings
Year Two was designed to build directly on Year One observations, shifting the emphasis from exploratory system establishment to repeatability, seasonal comparison, and targeted refinement. Additional variables were introduced to address limitations identified during the first research period, including root-zone oxygenation, growing media composition, and comparison with a heated control system.
Objective 1: Growth and Productivity of Cold-Resistant Crops (Year Two)
Methods:
Cold-resistant leafy greens and herbs identified during Year One were replanted within the established deep-water system. Replicated production areas were used to improve consistency in monitoring. Growth observations focused on plant vigor, leaf development, root structure, uniformity, and harvestable biomass. Marketable yields were recorded across winter, shoulder seasons, and warmer months.
To address summer stress observed in Year One, alternative growing media were introduced and evaluated. Media tested included:
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Lightweight Expanded Clay Aggregate (LECA)
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A blended media formulation designed to increase air exchange at the root zone
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A coconut coir–vermiculite blend, with formulations adjusted seasonally and designated as “winter mix” and “summer mix”
These media were selected to test whether improved root-zone aeration could reduce heat-related stress and stabilize production during warmer months.
Findings:
Plant growth during colder months remained consistent with Year One observations, with slow-moving water continuing to buffer root zones against freezing temperatures. During warmer periods, media containing LECA and blended substrates demonstrated improved root development and plant stability compared to earlier trials, indicating potential for reducing summer stress.
Seasonal coconut coir and vermiculite blends also demonstrated differential performance. The winter mix supported moisture retention and root insulation during low-light periods, while the summer mix improved aeration during higher temperatures. These findings suggested that seasonal media selection may function as an adaptive management strategy in passive aquaponic systems.
Objective 2: Deep-Water System Performance and Water Quality (Year Two)
Methods:
Water quality monitoring protocols were refined based on Year One experience. Sensors and manual sampling were used to track water temperature, pH, dissolved oxygen, ammonia, and nitrate levels throughout the year. A heated aquaponic system was also maintained as a control for comparative observation of plant growth and system response under stabilized temperature conditions. System adjustments related to aeration, feed rates, and flow management were documented as part of an adaptive management framework.
Findings:
Seasonal patterns in dissolved oxygen became more clearly defined in Year Two. Dissolved oxygen levels remained higher during colder months and correlated with improved root health, plant uniformity, and greater average head mass in winter-grown lettuce. During warmer periods, oxygen levels declined, reinforcing the importance of both media selection and root-zone oxygen management.
The heated control system demonstrated slightly improved winter growth relative to the non-heated system, likely due to both warmer water and a generally warmer greenhouse environment. However, the productivity difference was modest and did not represent a substantial enough advantage to offset the additional energy and infrastructure demands of heating.
The most significant difference between the heated and non-heated systems emerged during seasonal transitions. In the larger non-heated system, shifts between warm and cold conditions created a temporary lag in biological filtration performance, typically lasting one to two weeks. During this period, the conversion of ammonia into nitrite and nitrate slowed slightly as nitrifying microbial communities adjusted to changing water temperatures. This effect required closer observation of feed rates and nutrient cycling in the non-heated system, whereas the heated control moderated these transition effects.
Overall, the system remained stable under non-heated conditions, particularly during fall and winter production, while demonstrating the importance of attentive management during seasonal transitions.
Objective 3: Economic Viability of Non-Heated Aquaponics (Year Two)
Methods:
Operational costs, including labor, fish feed, seeds or seedlings, utilities, and routine maintenance, were tracked throughout Year Two. Infrastructure costs were treated as fixed investments. Produce sales were recorded through local markets and food hubs, and seasonal productivity was compared against operating inputs. The heated control system was used as a comparative reference for energy demand and operating costs.
Findings:
Economic analysis confirmed that energy inputs associated with heating remain one of the primary barriers to aquaponic profitability in colder climates. The non-heated system maintained substantially lower operating costs, particularly during winter months, while continuing to produce marketable crops.
Fish feed costs also declined during Year Two due to improved feeding efficiency and more responsive seasonal management. This reduction occurred without any observed negative impacts on fish health, growth, or water quality, suggesting improved feed-use efficiency and contributing positively to overall system economics.
Taken together, Year Two findings reinforced that the non-heated system can remain productive while operating under reduced energy and feed inputs, especially when crop cycles are aligned with cooler seasonal conditions.
Integration of Research and Education
Findings from both years informed Extension-style educational activities, including workshops, field demonstrations, consultations, lettuce tastings, and printed educational materials. Educational programming emphasized realistic system performance, seasonal constraints, crop selection, and economic tradeoffs, with particular attention to winter lettuce production, grow media selection, and the practical management needs of passive aquaponic systems.
Summary
Year One established the technical feasibility of non-heated, deep-water aquaponics in a temperate climate and identified the seasonal strengths and limitations of the system. Year Two validated those findings while refining system performance through targeted experimentation with grow media, closer monitoring of seasonal water quality dynamics, and comparison with a heated control system.
Together, the two years provide a multi-season assessment demonstrating that non-heated aquaponics can support viable cold-season production while reducing reliance on external heating. The research also identified practical strategies for managing warm-season limitations, improving root-zone conditions, and responding to seasonal biological transitions. These findings strengthen the case for passive aquaponics as a lower-input, climate-adaptive production model for moderate climates.
Lettuce Varieties Spread sheet - Sheet1
Objective 1: Evaluate the growth and productivity of cold-resistant plant varieties in a non-heated aquaponic system
Cold-tolerant plant species, including leafy greens, native greens, and herbs, were successfully established in a non-heated deep-water aquaponic system across multiple planting periods. Replicated plant groupings allowed for comparison across seasons and planting cycles, providing insight into crop performance under varying environmental conditions.
Across the 2025 production cycle, a total of 6,340 heads representing 10 cold-tolerant lettuce varieties were established in the system. The lettuce varieties evaluated included Green Butterhead, Marvel of Four Seasons, Freckles Lettuce, Mesclun Mix, Salad Bowl Blend, Red Plant Blend, Black-Seeded Simpson, Yankee Hardy Blend, Morgana, and Kaleidoscope Mix, resulting in a cumulative harvest of 2,583.95 lbs. Seasonal production totals reflected intentional scaling decisions aligned with market access. Summer plantings comprised 3,000 heads (1,218.80 lbs total yield), fall 1,550 heads (663.00 lbs), spring 990 heads (399.15 lbs), and winter 675 heads (303.00 lbs).
While aggregate biomass was highest during summer due to increased planting density, per-unit productivity demonstrated a different seasonal pattern. The average head weight across the entire dataset was 0.408 lbs. Seasonal disaggregation revealed that winter-grown heads achieved the highest mean mass at 0.449 lbs per head, compared to 0.406 lbs in summer, 0.403 lbs in spring, and 0.428 lbs in fall.
These findings indicate that total seasonal yield was strongly influenced by production scale rather than inherent biological limitation. When normalized by planting density, winter crops demonstrated strong per-plant performance despite reduced photoperiod and the absence of supplemental heating.
Plant growth and productivity exhibited consistent seasonal patterns when considered alongside system environmental conditions. Late summer months, particularly August and September, were associated with slower growth rates, increased plant stress, and lower individual head mass. Cooler fall and winter conditions supported renewed plant stability and uniformity, though overall growth rates slowed during periods of reduced daylight.
The higher individual head mass observed during winter aligns with concurrent water quality observations, particularly elevated dissolved oxygen levels under colder conditions. Conversely, slightly reduced summer head mass corresponds with periods of decreased dissolved oxygen and elevated system temperatures. These results suggest that the non-heated aquaponic system maintains stable plant productivity during cooler months and that lower winter biomass totals reflect market-driven production decisions rather than diminished system viability.
In addition to leafy green trials, culinary herb production was evaluated using two basil cultivars of Ocimum basilicum: Genovese basil and Osmin basil. A total of 1,000 basil plants were established in the non-heated deep-water aquaponic system (500 plants per cultivar). Harvest output was tracked using standardized market units (bunches) aligned with distribution channels.
From July through October, basil was supplied consistently to both farmers' markets and a regional food hub. Weekly harvest averages were approximately 50 bunches per cultivar (approximately 100 bunches total per week). Over the primary harvest window of approximately 16–18 weeks, this corresponds to an estimated total seasonal distribution of 1,600–1,800 bunches, or roughly 1.6–1.8 bunches per plant across the production cycle.
Varietal performance diverged under repeated harvest conditions. Genovese basil demonstrated stronger regrowth following cutting and maintained consistent marketable output throughout the season, while Osmin basil exhibited slower regrowth rates and reduced harvest frequency. Consumer response also differed between cultivars. While both varieties met quality standards for distribution, the purple Osmin basil showed lower market preference compared to Genovese, resulting in slower sell-through at farmers markets. These observations suggest that future production planning would prioritize greater planting density of Genovese basil to align biological performance with demonstrated consumer demand.
Objective 2: Assess the performance and stability of the deep-water aquaponic system in maintaining water quality parameters
The aquaponic system was originally designed for Nile tilapia (Oreochromis niloticus) under heated operating conditions. Tilapia require sustained elevated water temperatures, generally above 70°F, for optimal growth and survivability, making them suitable for actively heated systems but incompatible with the transition to non-heated operation.
Prior to the initiation of this research cycle, the system had been transitioned to koi (Cyprinus carpio), a cold-tolerant ornamental carp species. However, a prior equipment malfunction resulted in an acute thermal spike within the tank, leading to significant fish mortality due to temperature-induced stress. This event highlighted the importance of selecting fish species compatible with seasonal temperature variability in a non-heated aquaponic system.
Upon assuming management of the system, the tank was restocked with common carp (Cyprinus carpio), selected for their cold tolerance, environmental resilience, and suitability for non-heated aquaponic production. An initial stocking density of approximately 300 carp was introduced into the 15,000-gallon system. Over a three-year period, natural reproduction increased the population to approximately 423 fish.
Carp were selected due to their tolerance of seasonal temperature fluctuation and their relatively high nutrient output relative to biomass, which supports plant production in a large deep-water raft system without supplemental heating. The species has demonstrated strong survivability and stability under non-heated conditions, contributing to consistent nutrient cycling across seasonal production cycles.
A heated aquaponic system was originally proposed and implemented as a control to compare plant growth and system performance under stabilized temperature conditions. Maintaining heated water within an aquaponic system also contributes to a warmer overall greenhouse environment, which can 
further support plant growth during colder months. Trials conducted using the heated system did demonstrate slightly improved winter growth rates relative to the non-heated system. However, the difference in plant productivity between the two systems was modest and did not represent a substantial improvement in overall yield or crop quality. Because the primary objective of this research was to evaluate whether aquaponic production could remain viable without the use of external heating, these results indicated that the non-heated system was capable of supporting productive crop growth under regional winter conditions. The heated control system therefore did not demonstrate a sufficiently large advantage to offset the additional infrastructure and energy inputs required to maintain elevated water temperatures.
The most significant operational difference observed between the heated and non-heated systems occurred during seasonal transitions rather than during peak winter production. In the larger aquaponic system, shifts between cold and warm seasonal conditions created a temporary lag in biological filtration performance. During these transition periods, typically lasting approximately one to two weeks, the rate at which ammonia produced by fish waste was converted by nitrifying bacteria into nitrite and subsequently into nitrate temporarily slowed as microbial activity adjusted to changing water temperatures. This resulted in short-term fluctuations in nutrient transformation rates as the microbial community within the system adapted to new environmental conditions. A similar type of biological lag can also occur in planted growing systems when an entire crop is harvested simultaneously, temporarily reducing plant nutrient uptake and altering the balance between nutrient production and consumption.
To maintain stability during these seasonal transition periods, fish feeding rates required careful monitoring and adjustment. Under normal operating conditions the system was fed approximately one and a half scoops of feed per day, but during transition periods feeding was reduced to approximately one scoop, and during colder winter conditions feeding rates could decrease to as little as half a scoop per day as fish metabolic activity slowed. Reducing feed inputs during these periods helped prevent excess ammonia accumulation that could otherwise exceed the biological filtration capacity of the system.
One practical indicator of these transition periods in the non-heated system was the appearance of uneaten fish feed accumulating within the filtration system. This served as an early signal that fish metabolic activity and microbial nutrient processing had temporarily slowed. By recognizing this signal and adjusting feed rates accordingly, the system could be stabilized without long-term disruption to water quality or plant production.
Water quality monitoring demonstrated that the non-heated deep-water system maintained stable nutrient cycling across seasons. Dissolved oxygen levels were consistently higher and more stable during colder months, supporting root health and overall plant performance. During warmer periods, dissolved oxygen levels declined and corresponded with observed reductions in plant productivity.
Nutrient concentrations, including nitrate levels, remained relatively stable throughout the year, indicating that nutrient availability was not a primary limiting factor. Modest seasonal increases in ammonia were observed during winter periods and were attributed to reduced plant uptake associated with slower growth rates rather than a failure of biological filtration. Ammonia levels remained within acceptable operating ranges, and no negative impacts on fish health or overall system stability were observed.
Overall, results indicate that oxygen availability, rather than nutrient limitation, represents the primary constraint affecting plant performance under non-heated conditions during warmer months.
Objective 3: Determine the economic viability of non-heated aquaponics through cost-benefit analysis
Economic observations reflected seasonal production trends observed in plant growth and system performance. Spring and early summer production generated the highest potential revenue due to increased planting density and favorable growing conditions. Late summer declines in plant productivity corresponded with elevated system temperatures and reduced dissolved oxygen levels.
Across the 2025 production cycle, the system produced 2,583.95 lbs of lettuce from 6,340 plants, alongside an estimated 1,600–1,800 bunches of basil distributed through farmers markets and a regional food hub. Lettuce was marketed in two forms: loose-leaf bags and whole heads. Loose-leaf lettuce sold for approximately $5 per bag, while whole heads sold for $2–$3, depending on size. Based on typical blended pricing across farmers market and food hub outlets, the 2025 lettuce harvest represented an estimated seasonal market value in the upper four-figure range, depending on product form, outlet, and seasonal demand.
Basil pricing reflected typical seasonal market patterns. Early-season bunches sold for approximately $3 per bunch,
while late-season pricing declined to approximately $2 per bunch as herb supply increased across regional farmers markets. Despite this seasonal price compression, basil remained a consistent secondary crop contributing to overall system revenue during the July–October harvest window.
One of the most significant economic advantages of this system is the elimination of active heating. Conventional aquaponic systems in colder climates typically rely on supplemental heating to maintain fish survival and plant growth during winter months, representing one of the highest operating costs in aquaponic production. Operating the system without supplemental heating substantially reduced energy inputs while still maintaining year-round production capacity.
Fish stocking and feed costs were also relatively low. The system currently supports approximately 423 carp within a 15,000-gallon tank, originally stocked at a cost of less than $1 per fish. Feed consumption averaged approximately 1.5 cups of feed per day, with the system requiring two 50-lb bags of feed per year. Current feed costs are approximately $65 per bag, resulting in an estimated annual feed cost of roughly $130.
Labor demands remained relatively consistent across seasons, although summer months required additional monitoring of oxygen levels due to higher water temperatures. Despite these seasonal management adjustments, the system maintained stable crop production while operating under reduced input conditions.
Taken together, these results suggest that non-heated aquaponic production can maintain consistent crop output while operating with significantly reduced energy and feed inputs compared to conventional heated aquaponic systems. These findings suggest that non-heated aquaponic systems may represent a viable climate-adaptive production model, where aligning crop cycles with cooler seasonal conditions allows growers to maintain consistent yields while significantly reducing energy inputs and operational costs.
Research outcomes
Key Findings from Research on Passive Cold-Water Aquaponics
The research on passive cold-water aquaponics continues to demonstrate its potential to support sustainable agricultural production in the Western U.S., particularly in regions with moderate climates such as the Pacific Northwest. Ongoing operation of the system has provided additional insight into seasonal dynamics, system resilience, and opportunities for broader application beyond the primary research site.
A significant finding has been the continued success of cultivating cold-hardy lettuce varieties during the winter months. Although growth rates remain slower due to reduced daylight, plant development has not been limited by nutrient deficiencies or system instability. Beneficial microbial activity persisted throughout the winter season, allowing the system to function without interruption.
Quantitative production data collected during the 2025 growing cycle further reinforced these observations. Across the production year, 6,340 lettuce plants representing ten cold-tolerant varieties produced a cumulative harvest of 2,583.95 pounds. While the largest total harvest occurred during summer due to increased planting density, seasonal comparisons revealed that winter-grown lettuce produced the highest average head mass at 0.449 pounds per head, compared to 0.406 pounds during summer and 0.403 pounds during spring. This pattern suggests that colder water temperatures may support improved plant quality and biomass accumulation when oxygen availability is high, and plant stress from heat is reduced. These results indicate that the primary production limitations of passive aquaponics systems in temperate climates may be driven more by light availability and planting density decisions than by water temperature alone.
In aquaponics systems, fish waste is converted into plant-available nutrients through nitrification, a biological process driven by bacteria such as Nitrosomonas and Nitrobacter, which convert ammonia into nitrite and subsequently into nitrate. It is commonly assumed that cold water temperatures reduce fish metabolism and feeding rates while also suppressing bacterial activity, increasing the risk of ammonia accumulation. Contrary to initial expectations, significant ammonia accumulation was not observed during winter operation, even during periods of reduced fish presence and lower water temperatures. While modest seasonal increases occurred, ammonia levels remained within acceptable ranges and did not negatively affect fish health or system performance. These observations suggest that nitrifying bacteria within the system are more resilient to cold conditions than previously assumed and are capable of maintaining sufficient activity to support plant nutrient uptake. This reinforces the viability of passive cold-water aquaponics for year-round production of leafy greens without compromising water quality or plant health.
An unexpected yet promising outcome of continued system operation was the return of native frogs following the removal of active heating components. Their presence coincided with reduced insect pressure and a noticeable decline in algae accumulation within the system. Algae, if left unmanaged, can negatively affect aquaponics systems by reducing dissolved oxygen levels, particularly during warmer months when oxygen solubility in water decreases. Observations indicate that frog tadpoles may contribute to early-season algae control as water temperatures begin to rise in spring, indirectly supporting more stable dissolved oxygen levels during a period when the system is particularly vulnerable to oxygen stress. These interactions suggest that native biodiversity may play a functional role in supporting system balance, warranting further observation across seasons.
As the project has progressed, seasonal transitions have emerged as a critical factor influencing system performance. The most notable management challenges occurred not during peak summer or winter production, but during seasonal temperature shifts. During these periods, typically lasting approximately one to two weeks, the system experienced a temporary lag in biological filtration performance as nitrifying microbial communities adjusted to changing water temperatures. During this adjustment period, the conversion of ammonia produced by fish waste into nitrite and nitrate slowed slightly before stabilizing again once microbial populations adapted to the new temperature conditions.
Maintaining system stability during these transition periods required close monitoring of fish feeding rates. Under normal conditions, the fish were fed approximately one and a half scoops of feed per day. During transitional periods, feeding was reduced to approximately one scoop, and during colder winter months, feeding could be reduced further to roughly half a scoop as fish metabolic activity slowed. Uneaten feed accumulating in the filtration system served as an early indicator that microbial nutrient processing and fish metabolism had slowed. Adjusting feed inputs accordingly prevented ammonia accumulation and helped maintain system balance. These findings indicate that while passive aquaponic systems are highly resilient, they should not be considered entirely hands-off and benefit from attentive monitoring during seasonal transitions.
During warmer months, dissolved oxygen limitations remained a persistent challenge. Increasing mechanical aeration through additional air stones did not sufficiently resolve oxygen stress, indicating that aeration alone is not an adequate solution in passive systems. In response, experimentation with grow media revealed that root-zone conditions play a significant role in plant performance under warm-water conditions. Larger-particle grow media improved airflow around plant roots and helped compensate for reduced dissolved oxygen availability during summer months, while smaller-particle media performed well during winter, when dissolved oxygen levels were naturally higher, and moisture retention and root insulation were beneficial.
Grow media evaluated during this period included a standard mix of one part coconut coir to two parts vermiculite, porous mineral aggregates such as geolite, and aquaponics-specific substrates, including lightweight expanded clay aggregate (LECA) and similar porous materials. These media function both as structural root support and as biological filtration surfaces that support microbial communities. Continued experimentation is refining seasonal media selection as a management strategy rather than a fixed system component.
Winter production continues to focus on cold-hardy crops adapted to low-light conditions, with reduced sunlight identified as the primary limiting factor rather than nutrient availability or microbial performance. Ongoing trials are exploring methods to improve light utilization, including system layout adjustments and reflective strategies.
The lettuce variety trials also served as an important educational component of the project. During workshops, field demonstrations, and site visits, participating growers were able to observe the performance of multiple cold-tolerant lettuce varieties grown within the passive aquaponic system. These side-by-side comparisons allowed growers to visually evaluate differences in plant vigor, head formation, and seasonal performance under non-heated conditions.
Interest in these trials was particularly strong among hydroponic and greenhouse growers seeking crop varieties capable of maintaining productivity during colder months. As a result, the project produced a curated list of recommended lettuce varieties based on observed productivity, uniformity, and seasonal resilience. These findings provided practical guidance for growers interested in extending winter production cycles without increasing heating costs.
The lettuce trials also provided an accessible entry point for broader discussions about seasonal production strategies in controlled growing environments. By grounding educational conversations in crop performance that growers could observe directly, workshops were able to move beyond theoretical system design and focus on practical management strategies that producers could realistically adapt within their own hydroponic or greenhouse systems.
Community engagement expanded through workshops and discussions, leading to new collaborative research directions, including interest in taro production for Hawaiian community partners. The flexibility developed through grow media experimentation enabled a smooth transition into preliminary taro trials, demonstrating the adaptability of passive aquaponics systems to culturally significant crops.
In addition, the project is moving toward the deployment of smaller, modular grow-bed systems at two additional locations. One system is planned for installation at a WSU Extension site to support hands-on workshops, research demonstrations, and community education. A second system is planned for placement at a partner nursery to demonstrate the feasibility of backyard-scale aquaponics as a functional food oasis. These satellite systems will allow for testing system portability while expanding public engagement and illustrating how passive aquaponics can be adapted for household and community-scale food production.
Taken together, these findings continue to support passive cold-water aquaponics as a low-input, adaptable production strategy for moderate climates in the Western U.S. Ongoing research will focus on improving system stability during seasonal transitions, refining root-zone oxygen management through grow media selection, integrating native biodiversity as a functional system component, and expanding culturally relevant crop trials. By addressing these challenges and building ecological resilience, passive aquaponics systems can become a more robust and accessible model for sustainable food production.
Education and Outreach
Lettuce trials Workshop
Participation summary:
Objective 1: Increase awareness and knowledge of non-heated aquaponics among agricultural professionals and stakeholders in underserved communities
The project has prioritized in-person workshops, field days, and site visits to maximize hands-on learning and engagement. Multiple workshops have been held at the project site, targeting agricultural professionals, beginning farmers, community organizations, and stakeholders interested in lower-cost controlled-environment production systems. These sessions included interactive demonstrations of the non-heated aquaponic system, covering system design, seasonal management strategies, and plant selection for year-round production.
Participants were able to observe winter production cycles directly and see how the system maintained water quality, nutrient stability, and plant health without supplemental heating. Demonstrations included side-by-side crop observations, explanations of seasonal nutrient cycling, and discussions of how passive systems respond to temperature changes throughout the year.
Rather than launching a website as initially proposed, resources were directed toward direct engagement, ensuring participants gained practical experience and could interact with researchers to ask questions and troubleshoot challenges in real time. These in-person interactions allowed participants to explore system design decisions, observe crop performance, and discuss operational challenges such as seasonal oxygen management and fish feeding adjustments. As a result, participants developed a clearer understanding of how passive aquaponic systems operate in a temperate climate and how they differ from heated systems commonly used in commercial aquaponics.
These efforts strengthened understanding and built confidence in non-heated aquaponic production among diverse audiences, particularly growers exploring alternatives to energy-intensive greenhouse systems.
Objective 2: Provide educational resources and guidance to producers interested in adopting non-heated aquaponics
The project has provided personalized guidance and consultations for producers seeking to implement non-heated systems. Several farmers have visited the project site to observe system operations, review system layout and design, and discuss seasonal management strategies.
Interest from growers has been particularly strong around the cold-tolerant lettuce varieties trialed in the system. During site visits and workshops, participants were able to observe the performance of multiple lettuce varieties grown under non-heated deep-water aquaponic conditions. These side-by-side comparisons allowed growers to evaluate differences in plant vigor, head formation, and seasonal productivity.
As a result of these trials, the project team developed a curated list of lettuce varieties that perform consistently well in non-heated aquaponic systems. This information has become one of the most requested resources among visiting growers and has been shared during workshops and consultations as a practical crop selection guide.
In addition to growers exploring aquaponics for the first time, the project has engaged hydroponic and greenhouse farmers interested in adapting their existing systems to reduce heating costs. Discussions with these producers focused on seasonal production strategies, root-zone oxygen management, and crop selection for cooler water temperatures. These consultations fostered a knowledge-sharing network among growers, enabling participants to discuss practical challenges and management strategies relevant to their own operations.
The project is also developing a home-scale backyard system design intended to demonstrate how passive aquaponic principles can be applied at smaller scales. This model is designed to serve both beginning growers and community members interested in producing food in small spaces. Future research, informed by feedback from participants and community partners, will incorporate culturally relevant crops such as taro, reflecting community interest and expanding the system’s relevance to local food sovereignty and food access initiatives.
Objective 3: Disseminate project findings to the general public and engage diverse audiences through personal engagement
Dissemination efforts have focused primarily on direct, in-person engagement with producers, community members, and agricultural stakeholders. Multiple site visits, workshops, and hands-on consultations allowed participants to ask specific questions, observe system performance under real operating conditions, and discuss how lessons from the research could be adapted to their own operations.
Cold-tolerant lettuce varieties have consistently been one of the most discussed topics during outreach activities. Farmers frequently requested additional information about crop selection, seasonal planting strategies, and how non-heated systems could support winter production. These conversations often led to broader discussions about seasonal aquaponic management, oxygen availability, and how growers can align production cycles with environmental conditions rather than relying on energy-intensive heating.
In addition to producer-focused outreach, the project incorporated direct engagement with consumers through lettuce tasting events conducted at local farmers markets. These tastings were paired with outreach materials explaining the research project, the concept of non-heated aquaponics, and the cold-tolerant lettuce varieties being evaluated in the system. Market customers were invited to sample different lettuce varieties and learn about how they were grown within the passive aquaponic system.
These tastings served multiple purposes. They provided an opportunity to introduce the public to aquaponic food production while also allowing the project to gather informal feedback on flavor, texture, and consumer preferences among the varieties being tested. Customers who participated in the tasting were also given the option to purchase the lettuce, creating a direct connection between research production and market sales. This approach helped translate research findings into real-world consumer experience while expanding public awareness of alternative growing methods that reduce energy inputs.
In addition to aquaponic growers, hydroponic and greenhouse producers have shown significant interest in the project findings. Many of these growers are exploring ways to reduce operating costs while maintaining winter production capacity. Discussions with these producers focused on adapting existing greenhouse infrastructure to incorporate passive aquaponic principles, particularly around crop selection, seasonal management, and root-zone oxygenation strategies.
By prioritizing personal engagement and site-based learning, the project ensured that findings were communicated in ways that were practical, accessible, and directly applicable to real farming operations. This approach encouraged open discussion, peer learning, and collaborative problem-solving among participants.
Education Plan
The education plan emphasizes hands-on learning, personalized guidance, and community-informed research. Workshops, field days, and site visits provide practical, experiential education for farmers and stakeholders, allowing participants to interact directly with a functioning passive aquaponic system.
Curated resources developed through the project, including lettuce variety recommendations and system design guidance, allow producers to apply research findings directly within their own operations. These materials are complemented by in-person discussions that help growers interpret research results in the context of their individual farm conditions.
Personal engagement with growers and community members has also influenced the direction of ongoing research. Feedback from participants contributed to the expansion of grow media trials, further investigation into seasonal system transitions, and the introduction of taro as a culturally relevant crop. In addition, the development of modular backyard systems reflects participant interest in small-scale food production models that can support household food security.
By combining applied research with responsive education efforts, the project has established a model for community-centered agricultural research. This approach allows new knowledge generated through the system to be tested, discussed, and refined through direct interaction with growers and stakeholders.
Recommended Lettuce Varieties (1)
Objective 1: Increase awareness and knowledge of non-heated aquaponics among agricultural professionals and stakeholders in underserved communities
Workshops & Field Days:
Multiple workshops and field days were conducted at the project site, targeting agricultural professionals, community organizations, beginning farmers, and stakeholders interested in lower-input food production systems. These interactive sessions provided hands-on demonstrations of the non-heated aquaponic system, allowing participants to observe system operation, seasonal management strategies, and plant growth under real conditions.
Field days were particularly effective in demonstrating winter production cycles, where participants were able to observe firsthand how the system maintained water quality, nutrient stability, and plant health without supplemental heating. Demonstrations included discussions of seasonal nutrient cycling, crop performance under colder water temperatures, and practical management strategies for passive aquaponic systems operating in temperate climates.
Educational Materials & Engagement:
While formal video production and website development were deferred, educational materials including factsheets, handouts, and in-person presentations were developed to reinforce key concepts introduced during workshops and site visits. These resources focused on system design, seasonal management, and crop selection strategies for non-heated aquaponics.
Direct engagement allowed participants to ask questions, troubleshoot system design challenges, and discuss how passive aquaponic approaches might integrate into their own operations. Collaboration with community stakeholders, including a work-study student and a beginning farmer, further enhanced the accessibility of the material and helped ensure that the outreach activities reflected real-world farming challenges and decision-making.
Objective 2: Provide educational resources and guidance to producers interested in adopting non-heated aquaponics
On-Site Tours & Consultations:
Producers interested in implementing non-heated aquaponic systems participated in multiple on-site tours and consultations. These sessions allowed direct interaction with the operating system, enabling growers to observe seasonal performance, system management practices, and crop productivity under passive growing conditions.
Participants were able to examine system layout, nutrient cycling dynamics, fish management practices, and the role of environmental conditions in crop productivity. These conversations helped growers understand how passive aquaponic systems differ from heated systems commonly used in commercial aquaponics.
Cold-Tolerant Lettuce Varieties:
A highlight of this engagement has been the strong interest in the cold-tolerant lettuce varieties trialed within the system. During workshops and consultations, growers were able to observe side-by-side comparisons of lettuce varieties grown under non-heated deep-water aquaponic conditions. These trials demonstrated differences in plant vigor, head formation, and seasonal performance.
Based on these trials, the project developed a curated list of lettuce varieties that consistently perform well in non-heated systems. This information has been shared with visiting growers as a practical crop selection guide and has helped inform planting decisions among producers exploring passive aquaponic production.
Collaborative Learning & Knowledge Exchange:
The project also engaged hydroponic and greenhouse growers interested in adapting their existing production systems to reduce energy costs. Discussions with these producers focused on seasonal production strategies, nutrient management, root-zone oxygenation, and crop selection for cooler water conditions.
These interactions fostered a knowledge-sharing network among local growers, enabling discussion of challenges and practical solutions while reinforcing best practices observed through the research system.
Objective 3: Disseminate project findings to the general public and engage diverse audiences through personal engagement
Hands-On Engagement:
Dissemination efforts focused primarily on direct, in-person engagement rather than digital media. Farmers, community members, and agricultural stakeholders visited the project site to observe system performance, ask questions, and discuss how lessons from the research could apply to their own operations.
These site visits allowed participants to observe the aquaponic system under real operating conditions, including winter production cycles and seasonal management strategies.
Market-Based Outreach and Lettuce Tastings:
In addition to producer-focused outreach, the project incorporated consumer education through lettuce tasting events conducted at local farmers markets. These tastings were paired with outreach materials describing the research project, the principles of non-heated aquaponics, and the cold-tolerant lettuce varieties being evaluated within the system.
Market customers were invited to sample different lettuce varieties and learn how they were grown within the passive aquaponic system. The tastings provided an opportunity to introduce the public to aquaponic food production while also gathering informal feedback on flavor, texture, and consumer preferences among the varieties being tested.
Customers participating in the tastings were also given the option to purchase the lettuce, creating a direct connection between research production and real-world market sales. This approach allowed the project to evaluate consumer response while expanding public awareness of alternative growing methods that reduce energy inputs.
Practical Impact:
Producers consistently reported that hands-on demonstrations, guided tours, and personalized consultations were particularly effective for understanding non-heated aquaponic systems. Interest has been strongest in lettuce variety selection, system layout, and seasonal management strategies. Several growers expressed interest in adapting aspects of the system design or crop selection strategies within their own greenhouse or hydroponic operations.
Community Network:
These personal engagements helped create a growing network of producers and stakeholders interested in low-input aquaponic production. Conversations among participants often continued beyond the workshops themselves, facilitating peer-to-peer learning and ongoing discussion about seasonal system management and sustainable production approaches.
By emphasizing in-person engagement, the project ensured that research findings were communicated in ways that were practical, accessible, and directly applicable to real farming conditions.
Quantitative & Qualitative Findings
Engagement:
On-site workshops, tours, and consultations engaged more than 20 participants to date, including agricultural professionals, beginning farmers, and hydroponic and greenhouse producers interested in alternative production strategies. Participant feedback consistently highlighted the value of hands-on observation and direct interaction with a working system.
Effectiveness:
Participants reported increased confidence in understanding non-heated aquaponic systems and the management strategies required to operate them successfully. Many participants expressed interest in applying elements of the system design, crop selection strategies, or seasonal management approaches within their own operations.
Crop-Specific Impact:
Lettuce variety trials generated particularly strong interest among growers. As a result, the project developed a curated list of lettuce varieties suited to non-heated aquaponic systems. This resource is now actively shared with interested producers as a practical guide for crop selection in passive aquaponic production.
Community Reach:
Direct engagement with farmers, community members, and agricultural stakeholders has strengthened collaboration and trust within the local agricultural community, fostering a knowledge-sharing network that supports broader exploration of low-input aquaponic practices.
Conclusion
Through a combination of workshops, field days, site visits, farmers market outreach, and personalized consultations, the project has successfully increased awareness and knowledge of non-heated aquaponics among agricultural professionals, growers, and community stakeholders.
Hands-on engagement and direct observation proved to be the most effective methods for communicating research findings. By allowing participants to interact directly with a functioning system, the project helped translate research results into practical knowledge that growers can apply within their own operations.
The emphasis on cold-tolerant lettuce varieties, seasonal management strategies, and low-input production methods has been particularly impactful in guiding producers interested in adapting passive aquaponic approaches to temperate climates.
Education and Outreach Outcomes
Cold-Water Aquaponics_ An Exploration into Viability (5)
Recommended Lettuce Varieties (1)
Through the education and outreach activities conducted to date, several key recommendations have emerged for effectively disseminating research on non-heated aquaponics.
A primary insight is the need to explicitly address seasonality early in all educational efforts. Many participants initially approach aquaponics with the misconception that it functions independently of seasonal constraints. In response, outreach materials and presentations were adapted to first establish an understanding of seasonality in cold-water aquaponics, drawing clear parallels to traditional in-ground farming systems. Framing aquaponics within a seasonal context proved essential for grounding discussions, correcting misconceptions, and fostering realistic expectations among producers and stakeholders.
Another important recommendation is to center environmental and ecological concepts alongside technical system design. Outreach efforts that emphasized biodiversity within aquaponic systems, such as the role of plant diversity, microbial communities, and system balance, were consistently well received. Participants responded strongly to discussions that framed aquaponics as a living ecosystem rather than a purely mechanical production system. This approach helped reinforce broader sustainability goals and encouraged stakeholders to consider aquaponics as part of an integrated environmental stewardship strategy.
Integrating environmental education with practical, applied aquaponics techniques led to deeper engagement and improved comprehension. Stakeholders reported a greater appreciation for the interconnectedness of ecological systems and a clearer understanding of how low-input aquaponic practices can support resilience, sustainability, and long-term viability.
Based on these outcomes, future outreach efforts will continue to prioritize:
- Introducing seasonality as a foundational concept in aquaponics education
- Framing non-heated aquaponics within broader ecological and sustainability contexts
- Using hands-on demonstrations and real-world system performance to reinforce learning
To further disseminate project findings and expand their reach, I plan to apply to present this research at the November Tilth Conference, where agricultural professionals, educators, and producers can engage directly with the results and lessons learned from this project. Presenting in this setting will allow the findings to inform a wider audience and contribute to regional conversations around climate-resilient, low-input food production systems.
Knowledge: Farmers now understand that cold-water aquaponics has seasonal cycles similar to traditional farming.
Attitude: They view aquaponics as a sustainable complement to traditional agriculture rather than a year-round replacement.
Skills: Farmers have learned to balance system components, manage nutrient cycles, and enhance biodiversity.
Awareness: They are more aware of aquaponics' environmental benefits, including water conservation and sustainability.