WHY IS THE NITROGEN CYCLE SO IMPORTANT TO AQUAPONICS?
By John H. Musser
LET’S GET THE KEY BASICS DOWN FIRST!
ALL Aquaponics experts agree: the most important thing to be mastered in aquaponics is the “NITROGEN CYCLE.” Without conquering this hurdle, you may find yourself face-flat on the aquaponics racetrack and we definitely don’t want that!
So, today we will learn about one of the main building blocks in the aquaponics world. Think of it this way:
YOUR BALANCED AQUAPONICS SYSTEM IS LIKE AN ORGANIC CHEMISTRY LAB!
For those of you who hated chemistry (and biology and physics and the like), let me assure you – the whole process is A LOT simpler than you would think!
1. First off, the fish eat their food like champs (if you’ve ever watched these little creatures feed then you know what I’m talking about!) and, after digestion, excrete organic waste matter in the form of urea, uric acid and faeces/Feces. They also release ammonia as part of the gas exchange that occurs through respiration.
2. Heterotrophic bacteria (see: http://en.wikipedia.org/wiki/Bacteria), which are beneficial bacteria, assist in breaking down the waste material in the water. They do this by consuming the fish waste and uneaten food and converting them to ammonia and other inorganic mineral compounds.
3. This process greatly increases the amount of ammonia in the tank and, when it reaches a certain level, bacteria (Nitrosomonas) begin to take over the system.
4. As the numbers of these bacteria build, the ammonia is converted to nitrite. Nitrite (NO2-) is formed when Nitrosomonas sp. bacteria oxidise ammonia produced by fish and decomposing organic matter. Although it is less toxic than ammonia, elevated levels still present a threat to fish health. Prolonged exposure to low levels can lead to stress and is often associated with stress-related disease such as bacterial ulcers and fin-rot. As the ammonia levels dip, the nitrite levels increase.
THE NITRITES (like ammonia) ARE TOXIC TO FISH!
5. The presence of nitrites attracts the bacteria, nitrospira. Nitrospira convert the nitrites into nitrates, which are generally harmless to the fish and excellent food for your plants!
When the nitrite levels in the water reach a certain point, nitrite-oxidizing bacteria colonize the system and convert the nitrites to nitrates this is what we want, plant food! See Nitrospira here: http://microbewiki.kenyon.edu/index.php/Nitrospira
6. The plants consume the nitrates (and other compounds) and as they grow and are harvested, nitrogen is removed from the system.
7. Eventually, the system reaches the point where the various aspects of the nitrogen cycle happen simultaneously. As long as the fish are fed (and things remain in balance), the cycle continues.
Hopefully, that wasn’t confusing at all! Placing this cycle as the basis of all your thinking will greatly benefit you in the long run.
For example, it will help you remember to scoop out uneaten food so that that food will not sink to the bottom, turn into large amounts of ammonia and poison your fish.
It will remind you to be careful when you harvest lots of plants at once so you don’t kick your entire empire out of balance and will also help you keep your eye on LARGE water changes. (It is best instead to top your tanks off with a little bit of water every other day than to introduce gallons of new water when it’s too late!)
Just as easily, remember this: “Water in an established, balanced Aquaponics system is nature working in symbiotic harmony.” Jhm.
The illustration above is NOT ours and it has been disconnected from its home and now found on several sites. If the owner will inbox me I will gladly give credit as yours is the ONLY one that is accurate/up to date on the net. You give credit to the microbe Nitrospira which all others do not, great job, A MASTERPIECE!
Yours for sustainability, John Musser
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