The word “aquaponics” is a combination of the words aquaculture (the raising or farming of fish for food) and hydroponics (growing plants in a liquid nutrient solution rather than soil). Aquaponics can be defined as: a system of aquaculture in which the waste produced by farmed fish or other aquatic animals supplies nutrients for plants growing hydroponically, which in turn purify the water.
To simplify: Fish poop = awesome organic fertilizer.
In aquaponics we take advantage of the unique symbiotic relationship between plants and fish. Water is pumped from the fish tank to the plants, where beneficial bacteria in the grow bed convert the ammonia (NH3/NH4) produced by fish waste and excess fish food into nitrites (NO2). Those nitrites are then converted into nitrates (N03) that the plants use up as fertilizer. The water returning to the fish tank has been filtered both mechanically (by the grow media) and biologically (by bacteria). This is all done by way of the nitrogen cycle.
Nitrogen rich fish waste breaks down into ammonia which is extremely toxic to most fish. The nitrogen cycle is the biological process that converts this toxic ammonia into other less harmful nitrogen compounds, and then into the nitrates that we want for our plants. In aquaponics we rely heavily on three specific families of beneficial bacteria to do this: Nitrosomonas, which convert ammonia/ammonium to nitrite, and Nitrobacters along with Nitrospira, which convert these nitrites to the nitrates that our plants thrive on. So when you hear someone mention the “cycling” of an aquaponic system, they’re usually referring to the process of establishing these colonies of beneficial bacteria needed in the grow bed to convert fish waste into fertilizer .
Compared to traditional soil gardening, aquaponics is more efficient in every way. The constant supply of water and nutrients available to the plants ensure that growth rates are rapid and yields are more than impressive. Typically, a mature plant in a well-cycled system will produce 2-3 times as many vegetables as it would if it were in soil. In addition, we’re able to harvest these vegetables in about half the time, thanks to the dramatic increase in the rate of growth we get with aquaponics. This speedy growth is especially noticed in leafy-greens and herbs. (My sweet basil, mint and butter crunch seem to grow faster than I can cut them back)
In an aquaponic garden, standard plant spacing is a thing of the past. Another benefit of the constantly replenished supply of nutrients to the roots, is that the plants don’t end up competing for them like they do in soil, where the nutrients are usually limited. This allows us to place up to 3 times as many plants per square foot in an aquaponic grow bed than we’d be able to plant in a soil garden of the same size.
Soil pests and burrowing critters are also nuisances we don’t have to worry about in an aquaponic system. By replacing soil with a more solid grow media like lava rock or Hydroton, we greatly reduce the amount of unwanted pests. That’s not to say you’ll never have to deal with an occasional aphid or catapillar, but the effort you’ll put into pest control with an aquaponic system is minimal to nonexistent compared to a traditional soil garden.
The absence of soil also means no weeds, no tilling, no cultivating, no irrigating, and no compost shredding. Seeding, planting and harvesting is all it takes to put clean organic food on your plate, and with aquaponics this can all be done at waist level, rather than on your hands and knees in the dirt.
Aquaponic gardens use up to 90% less water than conventional soil gardens. If you live here in California you can see how that is extremely important. Some counties are implementing fees of up to $500 per day for excessive water usage. A large number of communities here in the Coachella Valley are now requiring a 36% cutback in order to avoid extra charges on the bill.
We’re able to conserve such a large amount of water by simply recirculating and reusing what would otherwise be lost to evaporation and ground absorption. We do this by directing the flow of water from the fish tank, over the roots where the nutrients are absorbed by the plants, then back into the fish tank where more nutrients can be collected by the water and the cycle can be repeated. Almost all of the water replaced when topping-off your aquaponic system, is water that’s used by the plants for growth and transpiration.