The Nitrogen Cycle - Cycling Your Pond Filter

Establishing and maintaining strong Biological Filtration in your pond before adding a large number of fish is very important to keeping healthy fish and a healthy pond.  The Nitrogen Cycle, often referred to as "cycling" is the most important process when first starting your pond.  It is the process in which beneficial bacteria becomes established in your pond's filtration system and will assist in the converstion of toxic Ammonia into non toxic Nitrates.

Stage 1: Ammonia is produced

When you first place your koi in the pond, there is always a risk of the water becoming rather foul in just a few days. This is because the fish 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 in most cases 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: Ammonia is converted to Nitrite

When your fish were introduced into their new home, their waste started producing ammonia, as stated in stage 1. By about the 3rd 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 ammoniaunder control though. There are bacteria that grow in your pond that help to eliminate the toxicity of ammonia. This bacteria is not present when you first set up your pond 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, converting it to Nitrite. Nitrite is also dangerous to fish.

Stage 3 (Final Stage): Nitrite is converted to Nitrate

Once you have successfully established Nitrite in your pond, to complete this cycle, you need another bacteria known as Nitrobacter. This bacteria turns Nitrite into Nitrate.  Nitrate 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 pond can take a while to establish. If you have plants in your Pond they will help with the production of Nitrate, which will complete the cycle faster.

Testing Your Water

Your water should be tested during the cycling process in order to monitor your progress. We recommend the liquid test kits by API.  After your filtration is fully cycled you should have Zero Ammonia and Nitrite and a Nitrate reading somewhere in the 10-35ppm range.

Feeding Your Biological Filter

In order to start the cycling process you have to have Ammonia for the bacteria to feed on. Ammonia can be added to your new pond by either adding a small number of inexpensive fish or by purchasing household Ammonia from your local grocery store.In Addition to the Ammonia which your fish produce, the nitrification process relies heavily on sufficient levels of Carbonate Hardness (KH).  For further information on KH in your pond we highly recommend reading our post on the matter: The Importance of KH in your Pond

Do I need to add Bottled Bacteria To My Pond?

Nope.  Nitrifying bacteria occur naturally and it is not necessary to add such products.  Here at Koi To The World we have NEVER used any of these products and have no issues whatsoever maintaining healthy filtration.  

How long does it take for my filter to cycle?

Most ponds will take anywhere from 6-12 weeks to cycle.  The amount of time that it takes is largely dependent on the water temperature.  Generally, the warmer the water the faster your filter will cycle.  Aeration and sufficient levels of KH will help the process along as well.

When can I add Koi or Goldfish to my pond?

New fish can be added gradually after your filter has fully cycled.  Adding only a few fish at a time will reduce the chance of a potentially harmful Ammonia Spike due to the increased Biological load on the filtration.

Koi To The World offers a great selection of Healthy KOI, Butterfly KOI & Fancy Goldfish for your pond.  Give us a try today and we are positive you will be more than satisfied with your purchase!

  • Jun 01, 2015
  • Category: News
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