AQUAPONICS FOR PREPPING
By Anthony Faircloth
(Author’s note: Please note that the system I describe below is a large “backyard” aquaponics system and is not to be confused with an extensive commercial system.)
Imagine that you have the ability to walk to a building, such as a barn or a greenhouse or even an inside room like your basement, where you harvest a few pounds of fish. Right after you pull the fish out of the tank you take a few steps and harvest a salad by clipping off the leaves of several types of leaf lettuce, pulling a cucumber from its vine, and plucking a few cherry tomatoes. Life would be grand, right?
This is possible through an aquaponics system. Aquaponics is a merging of two agricultural sciences; AQUAculture, the raising of fish or other aquatic life in a closed environment, and hydroPONICS which is raising plants without soil.
The usual configuration of an aquaponics system uses a tank for housing the fish, while other containers called, ‘grow bins,’ are filled with a type of medium, like pea gravel. These grow bins are used to support the plants roots and more importantly gives a place for the nitrifying bacteria that clean the water to live. Often a sump tank is also used into which the water from the grow bins drain.
My large system, the one in which I am raising fish and vegetables, has a sump and uses a hydraulic dynamic called, “ebb and flow.” A medium sized continuous flow pond pump lifts the water from the sump to the fish tank. The water in the fish tank gravity flows from the fish tank into a series of grow bins, filling the grow bins and exposing the highly ammoniated water to the hungry nitrifying bacteria. The bacteria convert the ammonia to nitrogen.
The water fills the grow bin until it triggers an auto-siphon which creates a vacuum inside the siphon and sucks much of the water from the grow bin. The now cleaned water is sent back to the sump where the process starts over again. The bacteria cleans the water and the process of siphoning aerates the water, thus supporting the fish’s needs. Again, this process is achieved with one medium sized pond pump. It is sized to accommodate 200 lb. of fish and provides 192 square feet of growing area.
The Things I learned
There are a few things that I have learned from the several years that I have been building and maintaining aquaponics systems that I should pass on.
First, use a fish that research has shown works well. Tilapia is one such fish. It has a low dissolved oxygen need and more easily breeds in captivity. In my area of Florida, one must have a license to raise Tilapia and until recently I thought the purchase of the needed permits were beyond my means so in an effort to move on with the project without Tilapia I decided to work with catfish. Admittedly this choice has brought me little success. On the downside, catfish have a greater oxygen requirement than Tilapia but on the upside they can live unaided in our low winter temperatures.
Serendipitously, in the process of working with the catfish I have successfully raised feeder Goldfish from their initial weight of several ounces, to over a pound. The fish seem unstressed and healthy. Since Goldfish have an oxygen requirement that is higher than that of Tilapia, I can say with confidence that my system will easily accommodate the dissolved oxygen requirements for Tilapia. I suppose the ‘silver lining’ of my failure has been to force me to redesign my system to increase the dissolved oxygen levels to support catfish.
The second thing you need to know is much like the first. Though someone might be able to successfully raise any fruit or vegetable in an aquaponics system, in my experience there are some vegetables that thrive, some that can get by with a little help, and some that take more support than I have the time or desire to give.
Generally speaking, green leafy vegetables are a no-brainer for aquaponics. Most types of lettuce thrive on consistent water and high nitrogen levels as do cabbage, collards, broccoli and many of the other Cole crops. Cucumbers seem to thrive and to some extent, some melons. Cherry tomatoes grow well though I have had limited success growing standard sized tomatoes.
A couple of years ago I experimented with a thing that I eventually called a ”tea-bag” which was nothing more than a mixture of organic potting soils and amendments containing low levels of nitrogen and higher levels of the other nutrients. I placed this dirt in a cotton pillow case and submerged it in the sump. These additional nutrients increased the health of the plants without playing havoc with the water chemistry. I replaced it monthly.
When I started my journey into aquaponics there was very little information about this science but now the Internet is saturated with YouTube videos and articles. Research it for yourself then give it a try. Maybe in a few months you’ll be inviting the neighbors over to a fish fry complete with fresh tomatoes and Cole slaw!
Building An Aquaponics System (The Backyard Prepper Series) (Volume 1) by Anthony Faircloth is available through Amazon in paperback and Kindle download.