Image Credit: theaquaponicsource.com
I provide many tours of our greenhouse campus explaining the science behind aquaponics, which is a difficult concept to comprehend at times. I’ve realized that most people haven’t heard of aquaponics and don’t understand the details associated with this system of farming. Below I’ve outlined some points defining aquaponics and the science of this concept.
- Definition: Aquaponics is the combination of freshwater aquaculture (raising fish) and the cultivation of edible plants. The fish waste-enhanced water is used to nourish the plants and then is returned back to the fish pond in a closed loop system. The plants clean the water by up-taking the nutrients provided by the fish water in order for the water to be reused.
- The three main components of an aquaponics system are the fish, plants, and bacteria. It is very important to balance these three things to keep the concentrations of nutrients in check. The bacteria are extremely important because they convert the fish waste into a nutrient that is more easily used by the plants.
- All of the nutrients in an aquaponics system come from the food that the fish is given. The amount of nutrients that are available to the plants directly correlates with the amount of feed that the fish are consuming.
- The difference between hydroponics and aquaponics: Hydroponics is the cultivation of crops in a soilless system using synthetic nutrients to fertilize the plants. Aquaponics is also a soilless system but no synthetic fertilizers are used; the plants are fertilized solely by the waste that the fish excrete.
- The nitrogen cycle: The nitrogen cycle is the fundamental scientific concept behind aquaponics. The fish are fed fish food, and they excrete it mostly in the form of ammonia (a compound of nitrogen). Ammonia is toxic to fish and plants in high concentrations, but it is also absorbed by plants. Bacteria will oxidize the ammonia and convert it into nitrite and then finally nitrate. Nitrate is readily used by plants whereas nitrite is very toxic to fish. When the bacteria colonies are functioning properly this reaction takes place quickly so that there is almost no nitrite and enough nitrate to keep the plants happy.
Still have questions? Post a comment and I’ll respond right away.
written by Rachel Burmeister, Internship Coordinator 2011-2012
Thanks a lot for tthe valuable information. can you provide number of flood and drain cycle we need to maintain a day to effectively transform fish waste to nitrares. I know each system will be unique anf requirements will be different. I NEED ONLY BASIC GUIDELINES.
how long we need to keep in the flooded status? item 2 below
howmany times we need to flood. drain during one cycle?- item 4 below.
how long we need to keep the growbwd without water- item 5
Is my undesdtanding of one cycle correct as, 1- start pumping and flood, 2- remain flooded for certain period, 3-drain completely, 4-flood again and repeat steps 1,2,3, many times, 5- stop pumping keeping the grow bed without water for a longer period.
Regards
Ashraf
Hi Ashraf,
We use a 15 minute flood and drain cycle every hour as a general rule for our media beds, but you’re right, it will depend on your particular system. During your flood cycle, you will want the water level to submerge the plant roots. The fish waste is converted into nitrites and nitrates by beneficial bacteria that live on the surface of the media in your growbed, and your system will be best able to convert fish waste when you have a healthy population of these bacterias.
Also, keep an eye on our Education page – we will soon be offering digital classes you might be interested in. And please let us know if you have any further questions.
Thanks,
Ariel