Aquaponics is the raising of fish and plants in recirculating systems whereby the fish provide nutrients to the plants and the beneficial bacteria and plants help to return the water clean to the fish. It’s a highly productive eco-system with many extraordinary benefits, most notably its ability to conserve water with minimal if any discharge. While there is plenty of information out there about the benefits of aquaponics, let’s talk about some specifics regarding system design that could be particularly important for mitigating some of the risks and challenges often found with aquaponics. To provide some context and scale, I’m using my aquaponics facility, Flourish Farms which occupies a 3,200 sq ft greenhouse. However, these ideas are applicable to any scale system.
When the fish system is running on its own loop, the hydroponic system can also continue flowing via its own pump. In our farm, water pumps from the last deep water culture trough back to the first trough maintaining continuous flow through all four troughs. This can also be run through a second sump.
· Power failures and a lack of good backup, monitoring and alerting systems.
· Loss of water due to a blockage, overflow, rupture or operator error.
· Poor temperature control and water quality management. Variability in temperature can be highly stressful on fish and if you are not able to properly control temperature, fish may stop eating. If your fish stop eating this affects the nutrient dynamics in your system.
· Fish disease can also creep up quickly if the temperature, water quality and health of the fish are not being regularly monitored or you are not quarantining fish upon arrival from other sources.
Another advantage is that the hydroponic troughs (DWC) can be run at their own flow rate if so desired. In other words, when the fish and plant system is running together in normal operating mode using a single pump, the hydroponic pump could be used to circulate water at a variable flow rate through the DWC troughs as well. This requires the running of two pumps, but if increasing flow rate in the hydroponic troughs is desirable than the separate DWC pump and plumbing gives the operator the ability to do so. This could be beneficial in case water flow rates are too low through the troughs. Water quality parameters can also be managed independently and optimized for each system. For example, fish tend to like a higher pH and plants like a lower pH. Temperature could also be managed independently depending on the location, environmental controls, fish species etc.
When reconnecting the two systems, it will be important to ensure ammonia and nitrites have been fully oxidized and are at safe levels for the fish. Water temperature, pH, Alkalinity and other factors affecting water quality may not be properly aligned between the fish and plant system so adjustments to these levels may be necessary to make a seamless transition and minimize stress on your fish. There may also be other elements of the hydroponic nutrient solution that could be problematic for fish at certain levels. For example we raise hybrid striped bass which are sensitive to potassium. It is always important to do your homework when you are considering adding something to your aquaponics environment. Thinning out the solution and exchanging with fresh water may be required to help reduce any potential toxicity and allow you to safely reconnect both environments.
JD Sawyer, Colorado Aquaponics