Rushing Waters Aquaponics Feasibility Study

PROJECT BACKGROUND

Rushing Waters is a flow-through trout aquaculture farm which grows approximately 100 tons of fish per year in 54 ponds.  It also hosts the Trout House, a small upscale restaurant and retail store.

A number of years ago, Rushing Waters made the choice to stop feeding hormones and antibiotics to our fish.  This was a bold step at the time, though it has since become the industry standard. 

Frosty Fish has been involved in aquaponics for a number of years and focused on sustainable and low-energy-use operation.

PROJECT DESCRIPTION

GOALS

The goals as defined in our application were related to the final stage of our aquaponics project, in which we would scale up to a large commercial size for supply of vegetables to regional distributors.  Because we are still in the research phase (which the SARE grant was used to kick off), those goals are still in the future.

The goals for this phase of our project (while not specified in the grant) were as follows:

• Construct a four-season greenhouse with pest control suitable for the growing of green vegetables
• Construct an aquaponics research station which allows for trials comparing different vegetables and different nutrient sources

PROCESS

Our project took place in the following four iterative and inter-related stages: research, design, procurement, and construction.

Research

This stage took the longest of any of the stages, and in reality began several years before applying for the SARE grant.  We include it here because it’s an area where many people looking into aquaponics fail to spend sufficient time and effort. 

Aquaponics is a challenging area to work in, and even more challenging to innovate in.  The reason is that it combines three areas, each of which can take a lifetime to master.  These three areas are as follows:

• Aquaculture: Fish farming is a complex and high-risk farming practice which requires management techniques completely different from other types of farming
• Hydroponics: Hydroponics is a farming discipline which takes many years to become proficient, and in which you must always keep learning and improving to stay ahead of the curve and maintain profitability.  Successful practitioners keep their secrets and unearthing best practices is not a simple task.
• Microbiology: Combining aquaculture and hydroponics creates a biological interface that requires you to develop expertise in areas typically only understood by marine biologists and wastewater engineers.

For this project, Jeremiah read over 100 academic papers, and participated actively in three different online forums over a period of five years.  This was a winnowing and sifting process, as the aquaponic farming space includes a lot of over-enthusiastic idealists whose claims far exceed their technical and business experience and acumen.  After this, he made contact with many of the world’s premier aquaponics and aquaculture researchers and practitioners, as well as a number of wastewater engineers, and had long conversations over the course of about a year in which he discussed all aspects of this project.  Finally, he visited all of the other large aquaponics farms in Wisconsin and interviewed the farmers about their methods and challenges.

All of this research was completed before spending a single dollar on construction.

The research, however, did not stop once construction began.  As problems, challenges, and unknowns popped up during construction, we continually went back to the internet and to the experts with more questions and seeking more information.

Our primary sources included (but were not limited to) the following.  We do not include the names of farms here due to our desire to respect their privacy.

• The Earthan Group and Paul van der Werf
• Dr. Wilson Lennard
• Dr. James Rakocy
• Dr. Steve Summerfelt
• Dr. Paul Adler
• Dr. Kenneth Semmens
• Dr. Mark McMurtry
• The University of Wisconsin wastewater engineering department
• Vlad Jovanovic of Atria Aqua Gardens
• John Burgess
• Andrew Berna of Paradigm Gardens
• aquaponicsnation.com
• community.theaquaponicsource.com
• backyardaquaponics.com

Design

Once the research was largely complete, the design was much easier.  Despite this, we still spent significant time in this area because experience taught us that we could avoid a lot of expensive mistakes by working through as many issues as possible before purchasing equipment or breaking ground.

First we used Google Earth to download a scaled map of the site, which we printed out and laid out several design options using an architectural scale.  Walking the site together with the owner and his business partner who has greenhouse design experience, we selected a layout, orientation, connection points with the electric grid, and entry points to a source of fish pond water.

With the basic layout done, we designed a 3D model of the greenhouse with endwalls and the basics of the aquaponic systems using Sketchup.  This allowed us to identify and understand space constraints, endwall construction options, and mechanical, electrical, and plumbing system space conflicts.  It also provided an easy way to make printouts which we could run past greenhouse experts to ask educated questions about the best option to choose.  This model took about 12 hours to build (we have some limited prior Sketchup experience), but saved much more time than this on the construction process. 

Procurement

We initially applied for this grant under the understanding that we would be purchasing a new greenhouse.  However, after doing some research online, we found that used greenhouses were significantly cheaper and there were several in the area that could be had.  Visiting several, we selected a used greenhouse from about 30 miles away which included all the electrical and ventilation equipment.  Going this route took longer to construct, but saved a lot on materials.

We considered the possibility of hiring a greenhouse construction contractor to build the greenhouse for us.  In retrospect, this may have been the best way to go, as it would have saved a significant amount of time and labor.  On the other hand, wrestling with all the design and construction choices taught us a lot about the process and forced us to understand all the tradeoffs and issues involved.

Because we were building a one-of-a-kind system, we needed a lot of products from a lot of different sources.  Some of these had lead time and had to be ordered ahead of time, and others could be purchased locally.  The sources we used for most of our products area as follows:

• Menards
• Anick Lumber
• Allied Aqua
• Pentair Aquatic Ecosystems
• eBay
• Craigslist

Construction

This portion of our project took much longer than we had anticipated.  This was in part because the designer and construction manager only had one day per week available to work on-site.  It was initially anticipated that he would work full-time on this project, but he was unable to work out an agreement with the Rushing Waters ownership group to justify full-time employment.  This forced the construction process to take seven months instead of two.

There were advantages to this extended schedule, however.  Because the designer had six days in-between construction days, he had ample time to explore additional design options and order additional products in time for the next week’s work.

The construction schedule progressed as follows.  All dates are 2015.

• April: Order water testing equipment and test for nutrient profile, and begin solids digestion experiments.
• May: Order sand, grade site, retrieve used greenhouse, and install temporary electric connection.
• June:  Erect greenhouse structure and frame end walls, build filters.
• July:  Build sand beds, finish endwalls, install mechanicals, trench electric power from power pole, and plumbing from the pond.
• August: Build deep water culture beds, install greenhouse poly film, install electrical system, connect mechanical equipment, and install Poly-vent and cooling system.
• September: Install plumbing, fill grow beds, order and start seeds, install aeration equipment, install filters, start solids digestion on-side, and run initial water flow tests.
• October: Rebuild sand beds (major design flaw), build float boards, start planting, build more-professional seed starting operation, and frame insect screening doghouses
• November: Monitor initial plantings, install insect screening, add small fan and damper for winter, air-seal endwalls, and install thermal mass storage.

PEOPLE

The primary individuals involved directly with this project were as follows:

• Jeremiah Robinson, owner of Frosty Fish
• Peter Fritsch, president of Rushing Waters Fisheries
• Justin Evans, farm manager from Rushing Waters Fisheries
• Gary Riggs, independent electrician and handyman

People involved in an advisory role are as follows (also listed above under “Research”):

• Paul van der Werf of The Earthan Group
• Dr. Wilson Lennard
• Dr. James Rakocy
• Dr. Steve Summerfelt
• Dr. Paul Adler
• Dr. Kenneth Semmens
• Dr. Mark McMurtry
• The University of Wisconsin wastewater engineering department
• Vlad Jovanovic of Atria Aqua Gardens
• John Burgess
• Andrew Berna of Paradigm Gardens

The following organizations provided support, encouragement, and a sounding board for this project:

• NCR-SARE – came for a visit, asked thoughtful questions, and produced a video
• Wisconsin Aquaculture Association – invited us to their conference and collected many of the region’s experts on aquaponics and aquaculture, which allowed us to have many conversations in which we floated and discussed options
• US Trout Farmers / National Association of State Aquaculture Coordinators – Held their annual meeting at Rushing Waters and took a tour of the aquaponics facility, providing helpful input on our design ideas.  One attendee was Dr. Ken Semmens, one of our primary advisors.
• Department of Natural Resources – the DNR wrote a very kind and thoughtful letter as one of the letters of recommendation for our grant

RESULTS

The primary goals of this portion of our aquaponics project were to build a working aquaponics research station inside a four-season greenhouse.  This was completed and is operating successfully.

We have begun supplying lettuce and greens to the Trout House restaurant and these have been enthusiastically received.  However, we have had to pause this effort for the winter in order to avoid serving greens which have taken up and stored excess nitrate during the months of limited daylight, as this is a health risk.  We will begin serving greens again in March, and may consider installing grow lights if winter production justifies this expense over time. 

Our greenhouse has already been used to provide some education, as it was one of the featured topics for the US Trout Farmers meeting hosted at Rushing Waters with about 50 participants.  A group of approximately 20 chefs-in-training from Chicago visited this summer and enjoyed their tour of the greenhouse.

We have started initial plant trials and have qualitative results.  The primary goal of our early testing was to determine if we could successfully grow plants at reasonable growth rates using digested fish solids or water from our fish ponds.  These results are as follows:

• Digested Fish Solids: We were late to the game in getting our digesters working and in use, because they were installed and put into operation in parallel with construction.  Because each batch of solids takes approximately a month to fully digest aerobically, we were unable to fully test their effectiveness this fall as we only had time to add one batch of nutrients which was insufficient to provide significant plant growth compared to our control system (standard hydroponics).  However, this portion of our system provided a useful second control as it was initially filled with pond water but not replenished with more pond water over time.  We were able to observe that after about three weeks the nutrients were depleted from this water by our seedlings and the growth from this system portion fell significantly behind the flow-through pond water based system.
• Flow-Through Pond Water: This portion of the system performed better than we had anticipated, though our test was not as scientific as it should have been.  Compared to the standard hydroponic system, the plants are growing about 2/3 as fast.  They are not showing any nutrient deficiencies, which is interesting given our known low levels of phosphorous.  This could be the result of our high water velocity, which Dr. Semmens found to have a correlation with plant growth.  One confounding factor is that we are not experts in hydroponic growing, so it’s likely that our hydroponic system isn’t producing the maximum growth that it could be.  In fact, we are sure that it isn’t because we are seeing nutrient deficiencies in that system and need to troubleshoot.  Another confounding factor is that we’re doing our first trials in the fall and winter, under limited light conditions.

We had also intended to do some water testing to measure the nutrient removal of the system.  We still plan to do this, though it turns out that we’re not able to measure these levels with the test kit that we purchased since its sensitivity is not sufficiently high.  We’ll have to send samples into a professional testing lab, which we haven’t done yet.

At this point, we haven’t discovered any areas where we would fundamentally change our approach.  We made a mistake in building the sand beds, which would have been nice to avoid.  There are other small areas which took longer than they should have or which we could do faster next time, but they were minor.

DISCUSSION

This grant brought Rushing Waters into an entirely new area of farming and business—growing green vegetables.  In that sense it was a major change.  Staff regularly stop in at the greenhouse out of curiosity and are starting to see themselves as a multifaceted growing operation (i.e. not just fish).  This hasn’t significantly affected operations yet as the effort has largely been undertaken by Frosty Fish.  However, as the project settles into long-term testing and operation, Rushing Waters staff will have to provide the regular monitoring, planting, and harvesting.

If it works out and we can grow vegetables profitably, then we’ll scale up and sell them wholesale.  If we can demonstrate that this also removes nutrients from the water, then that will be part of our DNR compliance strategy.  Those will be major advantages to the profitability of Rushing Waters over the long term. 

At present, the main advantage is the ability to provide the greens and herbs for the Trout House.

Under the current operation, the costs far outweigh the immediate benefits. Between labor and electricity, sales to the Trout House will not cover costs.  This was a known outcome, as this is an experimental station meant to test whether a system could be profitable at scale—a question we hope to resolve over the next two years.

We would not recommend that other farms implement an experimental station like we have.  If you want to know if it’s viable, you should simply ask us in two years and we’ll tell you.

PROJECT IMPACTS

We do not have hard economic data at this point, except for the fact that the greenhouse cost approximately $30,000 to construct.  Further data will be available starting in the spring and even more in two years.

OUTREACH

We have currently hosted one major event – the US Trout Farmers annual meeting.  Rushing Waters regularly hosts events for culinary students, weddings, and school field trips.  To the extent that they’re interested, we will take these groups through our greenhouse.  As time passes we may have to implement pathogen and pest management strategies that will prevent our bringing guests in, but at this point we’re fairly open.

We will serve our greens at our restaurant and will talk about how we grow them on-site, answering customer questions about how we grow them if they ask.

At this point we don’t have a lot of useful information to share that would be appropriate for larger circulation.  We’re also concerned about receiving a lot of requests for tours and more information, after publishing, especially since we don’t have conclusive data to share with anyone.  When our experiments are complete, we’ll be open to sharing whether our project was successful and whether it’s possible to grow vegetables on a trout farm like ours and whether it removes significant nutrients from the water.  How much detail it’s appropriate to share will depend on how large we scale to and the nature of the market for the products we’re producing at that time.