Using Aquaponics with Renewable Energy Resources to Create Sustainable Food Systems while Reducing Nutrient, Energy, and Water Costs

Final Report for OW10-301

Project Type: Professional + Producer
Funds awarded in 2010: $50,000.00
Projected End Date: 12/31/2010
Region: Western
State: Idaho
Principal Investigator:
Matt Johnson
Sustain Pro Management
Harry Ako
University of Hawaii
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Project Information


In Hawaii, lettuce production grew five-fold last year, and 80% of the tomatoes eaten were homegrown (National Agricultural Statistics Service, NASS). The producers responsible for this are project participants, and NASS attributed the increases to aquaponics and hydroponics. This produce was grown in recirculation systems, and precious fuel was not used in transporting it from the mainland. The University generated practical aquaponics technology and extended it to industry. All participating producers were introduced to sustainable agriculture and, arguably, the most successful built the largest aquaponics farm in the world.


Aquaponics is the symbiotic production of vegetables and fish. The project may be understood by participants via the Nutrient Flux Hypothesis (Baker 2010). Fish feed is fed to fish who metabolize it. They release the metabolites into the water where they are further metabolized by bacteria, and the products of this metabolism are taken up by plants and nourish them. Plants clean the water which is returned to the fish. Aquaponics is especially suited to island or urban environments because it produces three times the vegetables per unit area of land as conventional agriculture (Resh 2004) and uses only 1% of the freshwater used by traditional aquaculture (Rakocy 1989). Rakocy et al. (2004) developed aquaponics and receives credit for this. Its adaption by producers languished for 15 years. We have taken it upon ourselves to work out some of the fine details of aquaponics, to make it economically practical and to extend it to the public. This was initiated at a workshop/field day attended by more than 180 people (Appendix 2). At the workshop, the first draft of the workshop manual was handed out (Ako and Baker 2000).


Ako, H. and A. Baker. 2009. Small-scale lettuce production with hydroponics or aquaponics. College of Tropical Agriculture and Human Resources, Publication No. SA-2. University of Hawaii, Manoa, Hawaii, USA.

Baker, A. 2010. Aquaponics systems are governed by Nutrient Dynamics. Master’s Thesis. University of Hawaii at Manoa.
Rakocy, J. E. 1989. Vegetable hydroponics and fish culture - a productive interface. World Aquaculture 20:42-47.

Rakocy, J. E., D. S. Bailey, C. Shultz, and E. Thoman. 2004. Update on tilapia and vegetable production in the UVI aquaponic system. Pages 676-690 in R. Bolivar, G. Mair, and K. Fitzsimmons, editors. New dimensions in farmed tilapia: Proceedings from the 6th International Symposium on Tilapia in Aquaculture. Bureau of Fisheries and Aquatic Resources, Manila, Philippines.

Resh, H. M. 2004. Hydroponic food production: A definitive guide for the advanced home gardener and commercial hydroponic grower, sixth edition. New Concept Press, Inc., Mahwah, New Jersey.

Project Objectives:

a. Establish five demonstration sites.

b. Conduct research to develop management tools for farmers. This would allow simple and straightforward chemical assessment of how well farmers are doing with aquaponics.

c. Create a step-by-step guidebook to allow each producer to succeed with aquaponics.

d. Prepare a video that would allow step-by-step instruction as to how to generate an aquaponics business.

e. Conduct at least two field days at demonstration sites.


Click linked name(s) to expand/collapse or show everyone's info
  • Dave Campbell
  • Neil Ho
  • Jeff Koch
  • Fred and Brendon Lau
  • Edwin Otsuji
  • Ron Weidenbach


Materials and methods:

The project kicked off with a group meeting. At this meeting, the first draft of the how-to manual was passed out. A PowerPoint was presented, showing our vision of constructing an aquaponics system in a cost effective way. We shared our vision of managing the aquaponics system. This got the ball rolling, and farmers were invited to call us for help and request for us to send a student out to address questions. The meeting was followed by a site visit to each of the farms. Each site is different and producers had different ideas as to how to build their systems.

Meanwhile, extension-type research was done. We were familiar with the literature and had experienced limits of ammonia, nitrite and pH levels in our prior research and could use this knowledge to advise farmers as to management practices to change. However, oxygen needed to be researched, as aquaponics fish are held at high density and less than pristine oxygen concentrations are often observed. We found, and transferred the knowledge to farmers, that fish performance would decrease when oxygen was below 5 mg/L. Denitrification lessens the fertilizer quality of the water and occurs at dissolved oxygen levels of 2 mg/L or less. Minerals and micronutrients in the aquaponics water were new territory except for some hydroponics literature. This is some of the research that equipped us to be able to service farmers.

In terms of teaching method, one could characterize our most important method as the human touch. This had been developed over many years of teaching laboratory courses. Farmers were instructed to give us a call when they were getting started. The principal investigator and a student would visit the farm and obtain water chemistry numbers. In hindsight, errors were understandable because producers either had a plant background or a fish background. No one had an aquaponics background. Our assistance had an enormous impact because errors were so large. Two growers planted their systems under roof. Another used an aquarium air pump to aerate a 100 foot fish raceway. This grower destroyed all of his fertilizer nitrate and his fish were performing sub par. He also killed a significant number of his fish by not addressing the issue of biofiltration. Specific scientific methods taught are addressed in greater detail in the text that follows.

Research results and discussion:

In the bigger scheme of things, lettuce production in Hawaii increased five-fold last year. This is according to the National Agriculture Statistics Service (NASS). It attributed the increases in aquaponics and hydroponics of three of this project’s producers. Tomatoes were 80% homegrown as well, and they are grown hydroponically. Using aquaponics and hydroponics production was sustainable and natural. These were shared with fellow producers and the public in a field day/workshop (Appendix 1). There is a great deal of interest in aquaponics now.

The sites and our work to assist at the sites will be described from the least successful to the most.

The first farmer was doing hydroponics. He had a relationship to Costco and, while generating good income, he was having a hard time keeping up with the needs of the store and had an energy problem. Due to the one month revocable leases in Hawaii, it is difficult to get the electric company to invest in wiring up remote areas. His electrical needs were met by a diesel generator which is very expensive.

Another farmer whose base was aquaculture also dropped out. He got started, purchased and installed solar power which he used to run his tanks, but dropped out when he found other employment and could no longer afford the time to do this project.

A third farmer is a chef by training, and his wife is a horse trainer. He built his system using plastic growbeds which added to the cost. He had to dip into his personal finances for the project. When we visited his site for the second time, we did the water scan. His pH, dissolved oxygen, ammonia and nitrite values were excellent, demonstrating chemically that he followed instructions of the how-to manual. He had not lost a fish and his nitrate values were very high. This and the log book kept on feeding were excellent. However, when we visited we immediately noticed poor, scrawny plants. He had built his system under roof and had assumed that since he could see in the day times, the plants would have enough light. We measured his light intensity at 1,600 LUX, and our research determines that an intensity of 40,000 LUX is needed for lettuce. He should be fine once he replaces the roof panels with transparent ones. He will use his vegetables at his restaurant.

Another farmer whose background was aquaculture had challenges. He had power issues and purchased a wind-powered electrical generator. As he was about to install it, he was told he needed an environmental assessment. He was also told that any money he saved using his wind turbine would have to be repaid via his land lease. Thus his wind turbine now sits idle, but he is moving forward. He built a series of eight fish tanks and four large tanks that function as grow beds. He had just begun stocking his fish. Upon our site visit, his plants did not look good. His fish tanks were not covered, and there was algae in the water. These observation immediately suggested that any plant nutrients generated by his fish was being used by the algae in the greenwater, and this would be consistent with emaciated looking plants. Water chemistry revealed excellent dissolved oxygen, pH, and ammonia but very low nitrate (2.9 mg/L). Our research has shown good results with nitrate levels of 15 mg/L or so. Once the tank water is no longer exposed to the sun and fish are being fed at higher levels, we will examine the water chemistry again and hopefully he will have better results. His will be a low nutrient system, and what we find will be new science for low nutrient systems. They may work.

A fifth farmer also just started. He is an old-fashioned vegetable farmer. He took a while to get started because he wanted to investigate the markets before he invested his time into aquaponics. He required some assistance from one of our students, who supervised his field hands in constructing his system. On our third visit after he had just started, we noticed etiolated watercress and lettuce, his fish tank water was exposed to the sun, and he fed only a little feed because his fish were mature and did not eat much. He had had them on hand as pets. Water chemistry was fine regarding dissolved oxygen, pH and ammonia. We gave him some of our fish and repeated our instructions to feed them to satiety. In the next visit his nitrate nitrogen had arisen to 65 mg/L and his watercress formed a thick lawn in his growbed. He is selling all the watercress he can grow at very good prices. We believe it is wonderful to see a farmer get such good prices for his products. In part, this is due to the fact that he had the foresight to grow an aquatic plant and this plant is of unique quality.

The sixth farmer started out with a landscaper background. He attended the first workshop and decided to get into aquaponics since the landscape business was slow due to the economy. When we were first called he had a 4 foot X 100 foot fish tank and five 4 foot X 96 foot raceways.

He said his lettuce was growing slowly. His fish tank was aerated with an aquarium pump just like our 50 gallon fish tank and dissolved oxygen levels were about 1 mg/L. This leads to denitrification (fertilizer nitrate is converted to nitrogen gas and is lost to the atmosphere). When apprised of these data he installed a 1.5 horsepower air blower and his nitrate levels rose with the increased dissolved oxygen levels. They were a satisfactory >10mg/L and he was able to sell lettuce. He chose health food stores and a high end grocery store (Whole Foods). He then undertook to obtain organic agriculture certification and parlayed profits from his five raceways to build about 20 raceways, some enclosed in net houses to exclude insects. At last visit, he harvests 15,000 heads of lettuce a month. He now grows lettuce, Japanese cucumbers, heirloom tomatoes and blueberries. He receives good prices for these products and sells his tilapia live also for good prices. He may be the biggest aquaponics farmer in the world. His website is

He wrote a grant and purchased Solar panels. Electricity is the biggest expense of an aquaponics operation. During the daytime he is off the grid.

The Aquaponics Manual has been completed. The videographer is completing the video project. We replaced the two farm visits with virtual farm visits, as workshops.

Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:

The two workshops/electronic field days constitute outreach. Copies of presentations done by the P.I. are available on request. They are embedded in the workshops/electronic field days.

Appendix 1.

Workshop Agenda: Doors Open and Registration begins at 08:30 with coffee and refreshments. Workshop begins promptly at 09:00 and will end at approximately 12:00

0900-0915 Introductions

0915-0935 Jim Hollyer: Update on On Farm Food Safety and Certification

0935-0955 Harry Ako: Economics of Aquaponics

0955-1005 Richard Ha: Hamakua Springs Country Farms, Hawaii

1005-1025 Paul Singelton: Waipoli Hydroponic Greens, Maui

1025-1040 Coffee Break

1040-1100 Tim Mann: Friendly Aquaponics, Hawaii

1100-1120 Fred Lau: Maris Garden, Oahu

1120-1140 Tisha Uyehara: Armstrong Produce

1140-1200 James Channels: Foodland

1200-1230 Questions and Answer Session

The workshop will be facilitated by Clyde Tamaru, Aquaculture Specialist CTAHR. Workshop participants will be asked “What kind of technical assistance is most needed from faculty at the University of Hawaii?”. Admission charge for the workshop is $10.00 per person and parking is free. Refreshments will be served.

There are a limited number of seats available and reservations and to reserve a seat please RSVP: Harry Ako, phone: 956-2012 email - [email protected], or Clyde Tamaru Phone: 342-1063, email - [email protected]. Please make checks payable to Research Cooperation of the University of Hawaii or (RCUH) and send to the following address: Department of Molecular Biosciences and Bioengineering, University of Hawaii-Manoa, 1955 East-West Road, Ag. Science 218, Honolulu, HI 96822

Appendix 2


When: November 21, 2009. 10:00 – 13:00

Where: Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa, 1955 East-West Road, Ag. Science 219, Honolulu, HI 96822

What: Aquaponics or integrated hydroponics is the symbiotic cultivation of plants and aquatic animals in a re-circulating environment. While an efficient use of resources the combination of producing fish and plants using fish effluent brings about its own set of challenges and opportunities. Significant amounts of technical information continues to be gathered and it is an appropriate time to share the latest findings.

Governor Linda Lingle and Chancellor Virginia Hinshaw examine an aquaponics unit at the Magoon Agriculture Research Station, July 6, 2009. Utilizing inductively coupled plasma atomic emission spectroscopy University of Hawaii at Manoa researchers examined nutrients used by commercially viable hydroponic production systems for lettuce. This was followed by determining the nutrient production of tilapia. Based on their findings, fish stocking densities and feeding intensities that are required for lettuce nutrition have been defined. The estimates of nutrient outputs and uptakes provide for a deeper understanding of nutrient dynamics in the tank effluent that are necessary for designing an efficient aquaponic system. Interestingly, some designs have been found to be suitable while some have not. After the workshop session a working system located at the Magoon Agricultural Research Facility will be visited.

Presentations will also be made on:

•College of Tropical Agriculture and Human Resources (CTAHR) publication entitled, “On Farm Food Safety:Aquaponics” which provides valuable advice on reducing the risks to your personal health and the liability to your commercial operation.

•First hand experiences on the trials and tribulations of designing and building your own aquaponics unit

•Impacts of shading on nitrogen availability in tilapia tanks.


•Dr. Harry Ako (professor) and Adam Baker (graduate student), both with CTAHR, will be discussing nutrient composition in hydroponic and aquaponic systems.

•James Hollyer, assistant specialist with CTAHR will be discussing On Farm Food Safety.

•Dr. Bradley “Kai” Fox , Postdoctoral Fellow with HIMB, will talk about his experiences in designing and building his own hybrid (gravel bed/raft) aquaponic system.

•Ms. Marissa Lee, undergraduate student with CTAHR, will show the impacts of shading on nutrient availability in tilapia production tanks.

Workshop will be facilitated by Dr. Clyde Tamaru, aquaculture specialist with CTAHR. There is a parking fee of $3.00. Admission to the workshop is free. Refreshments will be served.

The two latest CTAHR extension publications regarding aquaponics will be available for distribution.

There is a seating capacity of 50 individuals. To reserve a seat please RSVP: Harry Ako, phone: 956-2012 email - [email protected], Adam Baker, Phone 226-2238, email [email protected] and Clyde Tamaru Phone: 342-1063, email - [email protected]
Workshop is being sponsored by:

•Hawaii Aquaculture Association
•Aquaculture Development Program
•College of Tropical Agriculture and Human Resources
•Center for Tropical and Subtropical Aquaculture
•Western Sustainable Agriculture Research & Extension
Appendix 3

Aquaponics Manual
(May 10, 2012)
Harry Ako with Adam Baker, Kiara Sakamoto, and Sean Short
University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources, Department of Molecular Biosciences and Bioengineering
1955 East West Rd. Ag. Sci. 218 Honolulu, Hi 96822

Education and Outreach Outcomes

Recommendations for education and outreach:

Areas needing additional study

On hindsight, we should have expended more effort in facility planning at the front side. Farmers were apparently intimidated by building things and/or had ideas that differed from our prototypes. Our farmer #5 was the slowest and learned how to build a system once we sent a student over to work with him. Several farmers sought advice from commercial suppliers and ended up spending more money than they needed to.

The take-home lesson was that the work was immensely rewarding and trying to develop commercial enterprise is very difficult. Working with hobbyists or backyarders is much easier and much quicker but at the end one rarely gets anything lasting.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.