Aquaponics is a practical skill to learn for prepping now, while the ability to obtain all the pieces and parts exists. The technology of aquaponics combines raising fish with gardening vegetables only in water. (There is no soil used at all). This usually takes a dedicated room that is water resistant, a reliable continuous (read redundant) source of electricity, food safe tanks of various sizes (any material from plastic to glass), and a good source of water. With the drought in California, which is the part of our nation that supplies a major proportion of the vegetables we find in our stores, reaching epic proportions and potentially hitting historic norms (California is a desert historically), it may be very important to be able to supply your family with vegetables. Based on my experience with my system, I think I can grow anything I can get to sprout. Sprouting various vegetables out of the soil is a challenge all by itself that I won’t discuss here. Water usage in Aquaponics is very low at around 3 percent of a regular garden operation. California should convert to all Aquaponic farms immediately.
Most set ups are small scale, though very large scale, industrial aquaponics businesses have sprung up across the country. For the purposes of this article, I will discuss family-sized operations. My little system is capable of raising 500 pounds of Tilapia (fish) per year as the harvested biomass equivalent of 4000 heads of lettuce a year. This is WAAAY more than my family of six can eat. We have fresh salads daily, fresh fish on demand (literally fresh fillets), tomatoes off the vine in January, peppers, eggplant, peas, cabbages, and spices all year round here in very snowy country. Seeds are available everywhere. Tilapia MAY be available locally from someone like me (I sell them to smaller guys), but ordering them on the web will mean a big airfare, unless you live near a Tilapia farm. (Don’t mix other species with your Tilapia. Do not add snails, gold fish (particularly), or anything else, please.)
My Aquaponics Greenhouse
My garden is established in a 40’X16’ underground greenhouse design, known as a pit greenhouse. The floor of the greenhouse is eight feet below grade and is done in poured concrete with drains every eight feet along the center of the floor for drainage. The walls are eight-inch, reinforced concrete, which is mostly insulated (as we live in a cool climate to -30 in the winter) by dirt which moderates both hot summer temps and cold winter temps. Essentially the structure is a basement with a greenhouse ceiling. Having two inches of polystyrene on the upper four feet of the outer wall moderates winter freezing considerably, also reducing condensation from the very humid environment within on the cooler surfaces. The green house slanted roof above is made of two layer Lexan™ specifically made for green house applications. We used redwood beams wrapped in mylar (reflective) for the roof span. Even with the two layer roof, condensation all through the cool months cause it to rain every day in the greenhouse. This necessitates using all plastic, aluminum, glass, stainless, weather-proof wood and other material for fixtures, cabinets, and tanks, as well as outdoor rated electrical equipment. Big exhaust fans during the warmer month(s) automatically start when the temperature hits the 80 degree mark and shut off at 70. In the summer we extend a 40 percent shade cloth over the structure to reduce heat gain and excessive sunlight on the plants. Even tomatoes will grow under 60 percent full sun. Growing tomatoes is the pinnacle of success with aquaponics, so they are something to shoot for about a year from starting your system. New systems will not successfully grow them.
Any aquaponics set up may be scaled to suit the size area you have available for the operation. There are many different kinds of aquaponics systems, and I will talk only about my set up. It took me a year from inception of the idea to get it all built and working to the first crop. Again, each building situation will be different. Warm climates versus cold climates obviously have different requirements for maintaining year round operation (keeping things warm but not too warm and so forth). Alternative energy sources are obviously quite applicable for this technology if you can guarantee 24/7 water circulation to your operation. Our heating bill for the whole severe winter this year was 250 dollars worth of propane. It never got below 65 degrees all winter. There are some operations that utilize hot water from nearby oil wells for heat during the winter. Others use solar water systems, while others use solar electricity. I have 4000 watts of solar panels, grid tie in, and propane generator redundant backup, plus the ability to plug in a small gasoline generator if I have to. Again, 24/7 power is a requirement for aquaponics. If you don’t have this ability, you need to consider non-circulating hydroponics. A researcher/PhD at the University of Hawaii called Kratky has a video that explains that technique in detail. Greenhouse design is outside the scope of this discussion.
If you have had aquarium fish before successfully, you should be able to master the skills necessary to raise Tilapia in an aquaponic setting. (My wife and I used to own and operate a pet shop.) Tilapia fillets are sold in grocery stores all over the country and are almost all farm raised in ponds from warm areas. Some states prohibit their presence due to their ability to rapidly populate warm waters. Water under 58 degrees will render Tilapia sterile and unable to breed, so northern states have no such limitation. Tilapia are mouth brooders, and females will protect eggs and fingerlings IN their mouth when danger appears. They are hard NOT to breed, and over-population is sometimes a problem.
The Cooperation of Fish and Plants
The object is, of course, for the fish food to be processed by the fish, the fish then poop, and the poop converts via bacteria eventually into nitrate, which the plants consider fertilizer. Tilapia and plants living together need compromised water conditions. Tilapia are prolific breeders, if fed well and kept in proper water conditions. For aquaponics purposes, your water should have a pH of 6.4-7.0 and never be any higher than 7.2 because plants start to starve (unable to take nutrition from the water). Plus higher pH’s tend to make what ammonia is present in the water (from fish respiration and food/fecal decay) to be more toxic coming out of solution over pH of 7.0. Water temperature is also a compromise. Tilapia do better at 80 to 85 degrees. They grow very fast at that temperature. Plants don’t like it over 75 degrees, so that is where my system is set.
The size of your system will determine how many fish and how many plants you can grow. My system has eight fish tanks, consisting of two 125-gallon breeder glass tanks, two 40-gallon refuge tanks, and four 110-gallons plastic tubs for feeding out/growing the fish. That’s a total of 770 gallons of fish elbow room. There are three 70-gallon plastic settling/filter tanks, called clarifiers, that remove any large floating debris/fecal matter/uneaten food from the fish tanks and two anaerobic mineralizing tanks (40 gallons each) that catch small particles and then let them slowly turn into trace minerals under low oxygen conditions. Water from the mineralizing tanks flows into a small heavily aerated tank that drives off any CO2 from the water and adds O2 to the system. From there, the water flows to the plant raft tanks. My total tank capacity is roughly 2000 gallons. You can keep as much as one pound of fish for every two gallon of water in the system, but that is a maximum. Your milage will vary. More population means VERY close monitoring of conditions. With that many fish/that much feeding, things could go bad very quickly. You have to be meticulous about your water quality.
The water actually is on sort of a race track as it circles about. In my system, two 1” pumps push water from the last plant tanks (lowest part of the system) up to the fish tanks (highest part of the system). From there, water just runs down hill to the clarifiers (first filter tanks), from the clarifiers to the mineralizers (second filter tanks), then to the degassing tanks, then back to the plant raft tanks. When I drain water from the system, an automatic float lets in reversed osmosis (RO) water, which prevents an increase of total dissolved solids into the system. This necessitated a 1000 gallon a day RO filter, which wasn’t free unfortunately. You have to add your own salts to the water for pH buffering (the tendency of the water to be stabile at a certain pH level because of hardness). This is better than having hard water in the system and increasing its hardness due to evaporation and replacement. The only way to deal with that is to do regular (weekly) partial water changes (read work). The RO does a lot of that for you, though it doesn’t reduce overall water use. It just makes it so you don’t have to change water as much manually, which results in the loss of trace minerals you work hard to accumulate for the plants.
