The Nitrogen Cycle

Pond/Aquarium Nitrogen Cycle

When it comes to the Nitrogen Cycle, many of you think that it’s some huge complicated process in which you may never understand. But, there’s nothing to fear!

Here’s an easy to understand blog about the process. 

The Nitrogen Cycle, also known as “cycling” is the most important process when starting an aquarium/pond. It’s the process in which beneficial bacteria becomes established in your aquarium/pond in the filtration system that will assist in the conversion of TOXIC ammonia into non toxic Nitrates.

Stage 1:

When you first place your koi in the pond/aquarium, there is always a risk of the water becoming rather foul in just a few days. This is because the koi release their urine and feces in the water. Decaying food and plants also play a role in this process. These waste products break down and are converted into Ammonia. Ammonia is toxic to fish, especially in large amounts. A pond/aquarium is a closed system, which means that there is no way to get these toxins out without replacing the water. Without replacing water, ammonia can accumulate rapidly.

You can measure your ammonia levels by determining the PH of your water. You can do this by using a freshwater aquarium/pond testing kit. If the PH of the water is under 7, ammonia can still be relatively safe for your koi. However, if it’s 7 or over, it is no longer safe. A high PH level with ammonia present will stress your koi, and if not treated immediately, it can damage their internal organs, and ultimately lead to death.  

When ammonia starts to be produced, and it begins accumulating in your pond/aquarium this is the beginning of the nitrogen cycle.

Stage 2:

When your fish were introduced into their new home, their waste started producing ammonia, as stated in stage 1. By about the 3^rd week, without water changes, the water is most likely already toxic. If this is the case, a water change is needed. Water changes don’t always have to be done to keep the ammonia under control though. There are bacteria that grow in your pond/aquarium that help to eliminate the toxicity of ammonia. This bacteria isn’t present when you first set up your pond/aquarium and can take anywhere from weeks to months for it to have enough established to help neutralize the toxicity of ammonia. The bacteria present are called Nitrosomonas. This bacteria does eliminate ammonia, however, it turns it into another element called Nitrite. Nitrite is also dangerous to fish. 

Final Stage:

Once you have successfully established Nitrite in your pond/aquarium, to complete this cycle, you need another bacteria known as Nitrobacter. This bacteria turns Nitrite into Nitrate, which is NOT harmful to fish. This bacteria won’t develop until you have a bountiful colony of Nitrite. This is why the actual cycling of a tank can take a while to establish. If you have plants in your tank, they will help with the production of Nitrate, which will complete the cycle faster.

There are several products that can be bought at your pet store to start the cycling process. There are also several other ways to start the process such as adding household ammonia to your pond/aquarium, or adding a piece of raw shrimp.  If you chose these options, do NOT add fish to your pond/aquarium until the cycle is complete.

You can start the cycle as well by adding fish to your pond/aquarium, but it is not recommended, as those fish suffer ammonia burn and potential death.

When you test your water, you want a reading of:

0 Ammonia, 0 Nitrite, 10-25 Nitrate

If you do not have a Nitrate reading, your tank is not cycled!

Summary:

There are 3 stages in the Nitrogen cycle to understand.

1.      Ammonia is produced by fish waste and decaying plant/food matter.

2.      A certain type of bacteria consumes the ammonia and produces Nitrites, which are toxic.
3.      Another type of bacteria consumes Nitrites and turns them into Nitrates, which are not harmful.