The Nitrogen Cycle
Whether you are a long time fish-keeper or are new to the hobby, one of the most important things for you to know about and understand is the Nitrogen Cycle. Most hobbyists know this process simply as cycling, or New-Tank Syndrome. The Nitrogen Cycle, when referring to aquariums, is more of a process rather than an actual cycle. The end result of this process is the build-up of beneficial bacteria and nitrates in your aquarium and filtration system that break down ammonia and nitrogenous waste. So, what exactly is the Nitrogen Cycle?
The key to understanding the nitrogen cycle is to keep in mind that fish are living creatures. And living creatures need to do two things in order to survive; they need to eat, and they need to defecate. Well, this is where the Nitrogen Cycle begins. Typically, in the wild, fish live in a relatively large amount of water; they can live in ponds, lakes, rivers, or even in the open ocean. The advantage in this is that the water surrounding the fish is constantly moving and changing. This allows any sort of harmful build-up of waste or uneaten food to be flushed out of their habitat, bringing in a influx of clean water (with the exception of natural ponds,which, due to the higher surface area, allow for a freer exchange of harmful wastes out of the water). Unfortunately, this doesn’t happen in an aquarium. The water in your aquarium (at least in between water changes) is stagnant; it doesn’t have any place to go. Which means that any sort of fish waste or uneaten food also has no place to go. Depending on how long you typically go between water changes, this can be very harmful to your fish.
As fish waste (urine and feces) and any uneaten food builds up in your tank, it begins to decay and release ammonia. Ammonia in and of itself is highly toxic; fish can only tolerate as little as 2 ppm (parts per million) before their lives are in danger (which is also why it is so important not to use household cleaners on or around a fish tank; the ammonia in those cleaners can seep through the glass of your tank and leach into your water, killing your fish).
The good news is that there already exists in your tank specific bacteria that oxidizes ammonia. The bad news is that the result of that oxidation are nitrites, which are also highly toxic to fish. In fact, nitrites are even more harmful to your fish than ammonia; levels as low as 1 mg per liter of water can kill.
So how do you get these harmful nitrites out of your water? That’s where your filtration comes in. Growing on your (mature) filter media are bacteria that convert nitrites into nitrates. Nitrates are simply another form of nitrogen, but one that is arguably less harmful to your fish than either ammonia or nitrites. Fish are able to withstand a much higher level of nitrate in their habitat; nitrates can rise up to 20 ppm before they are harmful to your fish, and up to 5 ppm before they are harmful to your corals.
Of course, this is not to say that you want your nitrates to get that high – but it is nice to know that you have a little more buffer room than you do with ammonia or nitrite. So how do you lower your nitrate levels? Easy – a water change! Water changes are probably the most important thing you can do to maintain the health and happiness of your fish. We recommend at least a ten percent water change every week to make sure that your fish are constantly getting an influx of fresh, clean water. Be sure to use a special dechlorinator (we recommend Prime by Seachem) to remove any harmful chemicals from your tap water before you put it into your tank. As an added bonus, Prime also removes ammonia from your tank, as well as detoxifying nitrates and nitrites (keep in mind, however, that Prime should be used as an additive to help keep ammonia, nitrite, and nitrate in check; nothing will replace the benefit of a water change in keeping these compounds from reaching too high a level).
In summation, the nitrogen cycle is a three-stage process: (1) any fish waste or uneaten food begins to break down and decay, releasing harmful ammonia into the water; (2) the ammonia then begins to break down into even more harmful nitrite; (3) beneficial bacteria colonizing your filter media break down the nitrite into nitrate, a chemical that, although not nearly as toxic to fish as ammonia or nitrite, still should be monitored carefully to avoid reaching a deadly concentration. Water changes are the most important thing you can do to keep your tank healthy and to flush out the harmful byproducts of the nitrogen cycle. Be sure that you either have a test kit at the ready to make sure your water parameters are acceptable (or you can always bring a sample of your water down to the store, and we will be happy to test it for you). Taking fifteen to twenty minutes every week on testing and changing your water will save you lots of time and lots of money in the long run.
As always, if you have any questions regarding the nitrogen cycle or maintaining the health of you tank, feel free to call us at the store. You can also find us on Facebook. Good luck!
