Posted on July 20th, 2012

Outside the Box – Aquaponics

Aquaponics is a sustainable food harvesting system that combines aquaculture (the farming of aquatic organisms) with hydroponics (a method of growing plants using mineral nutrient solutions in water, without soil). In this aquaponics, the water from the aquaculture system is recycled to hydroponic plant-life whereby they take advantage of the vital nutrients added in the first step.

One of the most important aspects of an aquaponics system is the bacteria and its function in the nitrogen cycle. Fish excrete ammonia, which in a more natural setting would be absorbed, but in a home fish tank system, the ammonia needs to be extracted because it is harmful to them. Two types of bacteria aid in the conversion of ammonia into nitrites and nitrates (Nitrosomonas sp. and Nitrobacter sp. respectively). These nitrates are then cycled to the hydroponic plants where they use the nitrates to increase metabolic growth. Also important to both fish and plant-life is a stable pH which can be achieved by adding egg shells or calcium carbonate tablets to the systems.


Some may wonder about the efficiency of aquaponics versus a traditional hydroponic system. Researchers in Canada found that in the first 6-months of testing, the hydroponics system produced better results, but this is likely due to the lag time it takes aquaponic systems to build up the required levels of bacteria. By the 12-month mark, the aquaponic system out-performed hydro, and in some cases production levels had doubled that of hydro levels. Optimum production level was seen at the 2-year mark for aquaponic systems.

While aquaponics sounds like an “outside-the-box” idea, many believe it has its roots in ancient times. Mesoamerican agriculturists used a procedure called chinampa where small areas of arable land for the growth of crops were located in shallow lake beds in the Valley of Mexico. Commonly referred to as floating gardens, chinampas were found in the shallowest areas of lakes. Beds were constructed in these areas with mud, lake sediment and decaying vegetation to allow the plants to sit above the water, while their roots grew down through the nutrient rich emollient into the life-giving lake. Maize, beans, chili peppers and flowers were just some of the crops grown in the chinampas.

Today the system is more refined, and is typically comprised of: a rearing tank (for the fish); solids removal (catches uneaten food); a biofilter (where ammonia is converted into nitrates); the hydro subsystem (where plants are grown by absorbing nutrients); and the sump which recycles the water in the system from the lowest point.

Aquaponic systems have many advantages to consider: water conservation through recycling; organic fertilization of plants with fish emulsion; reduction in needed cropland; and efficient commercial installations that reduce food miles. And you might ask, “What are food miles?” This is a term that describes the distance it takes to get food from production to consumer; and it can be understood in tandem with a carbon footprint. So if you’re looking for an exciting hobby or you want to start growing your food to save money and eat healthier, perhaps you should give aquaponics a try. It is sure to give you a healthy new look at how we feed ourselves outside the box!

Justin Harmon

Staff Writer

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