When a hobbyist refers to cycling an aquarium he or she is referring to the process of establishing the Nitrification Cycle in the tank.
What is the Nitrification Cycle?
In an aquarium, it is nature’s way of breaking down waste and organic matter. Fish like all living things need to eat. When they eat they produce waste in the form of urine, feces, and un-eaten food (Bio-load). Waste by nature produces ammonia, which is toxic to fish. The next stage involves a nitrifying bacteria. These bacteria consume the ammonia as food and excrete their own waste product called Nitrites. This product is very toxic to fish. The next stage involves yet another bacteria that consumes the Nitrites. These bacterium convert the toxic Nitrites into a far less harmful product called Nitrates.
Nitrites (with an “I”) = the harmful toxic waste product
Nitrates (with an “A”) = the less harmful product of bacterium
These bacteria reside in your filter. There are some that live on the glass, gravel and decor, but most of the bacteria are found in your filter media. (Sponges,ceramic rings etc.)
Why do I need to Cycle my tank?
Without these beneficial bacteria, your fish will be subjected to high levels of Ammonia as well as Nitrite that are very harmful to your fish and can cause poisoning and if not addressed, eventually will cause death. It is important to assure your tank is fully cycled so it can handle the bio-load of your fish and not subject them to these toxins. New Aquarists often find themselves experiencing “New Tank Syndrome” which is caused by introducing fish into a tank in which this process has not been completed.
How do I Cycle my aquarium?
There are two methods of cycling an aquarium. You will need a Master Freshwater Test Kit in order to do both of these correctly (See the Why do I need to test my water FAQ).
1. The Fishless Cycle – This is the fastest, safest and most humane way to establish the bacteria you need in the tank. This method once completed will grow enough bacteria to handle the full bio-load of your aquarium provided it is not overstocked.
FIRST: You need to get a test kit. I use Aquarium Pharmaceuticals. You will need a NitrIte test kit, NitrAte test kit, Ammonia test kit and you should have a PH test kit just because it’s good to have. (you wont be looking at ph for cycling)
This is what you do.
If you have another tank in the house, something helpful would be to take a piece of sponge or a handful of gravel and put that in your new tank. This will help "seed" the tank and introduce some bacteria to help things along. If you do not have another tank, its not needed (just helpful).
NEXT
Get your hands on some common household ammonia. Make sure there are no additives or soaps in it. Just look at the ingredients. If there are no ingredients and the liquid doesn’t get foamy like soap when you shake the bottle, then it should be pure ammonia.
You will need to add about 3-4 drops of ammonia per 10 gallons of water.
Do this once daily until your ammonia reading pretty much reads 5PPM. Make sure to place the same amount of ammonia in each day. Anything more than 5ppm ammonia at any point, you'll only delay the completing of your "cycle."
Keep on adding the same ammonia dose and wait for a Nitrite spike. You will need to test the water at least every other day to keep track.
You are looking for your Nitrite to spike to about 3-5 ppm (parts per million). This should be near the end of the chart.
Once you get a Nitrite spike, you need to cut your ammonia additions in half. So keep adding ammonia every day, but half of the initial dosage.
This next part could take a while, up to a month or possibly more. Its different for everybody.
You need to wait until your Ammonia and your Nitrite readings drop all the way to Zero. Not almost to zero. They have to be at Zero.
Once this happens, check your NitrAtes. These should read anywhere from 20-80 ppm. Most likely it will be around 80 ppm.
So you have a reading of Ammonia – 0, Nitrite – 0, Nitrate – 80.
Nitrates should ideally be around 20 ppm for a healthy fish.
So you will need to do a heafty water change to remove the excess nitrates. For a reading of 40 ppm, do a 50% water change and for anything higher, do a 80% water change.
IMPORTANT: Do not siphon the gravel during the water change. It is not necessary since there is not waste and you need to keep the bacteria alive. (Once you have fish in the tank you will need to siphon the gravel)
Also make sure to condition any water you put back in the tank. You need to remove any chlorine or chloramines in the water to prevent killing your new bacteria.
Once you do the water change, check your readings again the next morning. If everything looks good, go get your fish
(Because of various factors, the actual length of cycling per tank could vary. Strength of ammonia purchased, use of "seeding" like gravel. There are many reasons that the length of your cycle could be different than someone else's. Just know that it WILL cycle eventually. Just be patient. You'll be glad you were)
2. Cycling with Fish – This is the more traditional method of establishing the Nitrification Cycle. The downside to this method besides having to subject fish to the cycle is that this method takes a lot of time (4 weeks and up), and can only handle the bio-load of the number of fish used to cycle the tank. Buy a few hardy fish like Roseys, and place them into the aquarium. Start by doing no water changes for 2 weeks. During this time the Ammonia will peak and you will begin to show a Nitrite spike. Once Nitrite is detected, do a 20% water change and leave again for 2 weeks. If all goes well and the fish actually survived the whole ordeal, you should be able to then start weekly 20-30% water changes as part of your regular maintenance schedule.
How do I remove the Nitrate?
The only way of keeping Nitrate levels under control is with weekly water changes of 25-40%, and a good vacuum of the substrate, followed by a good rinse of your filters as needed. Hang on Back FIlters (HOB) should be done every two weeks or so. However canisters can go a lot longer between cleanings. It is also a good idea to rinse all filter media in a bucket containing tank water. This will help prevent the loss of nitrifying bacteria. This needs to be done regardless of which method you use and is necessary to avoid Ammonia and Nitrite spikes due to overfeeding and other water quality related problems. Adding living plants can assist in keeping nitrates levels down, but be aware a lot of fish do find a live plant a tasty treat.
I Cycled my tank and I still get Ammonia and Nitrite spikes. Why?
Once the Cycle has been established, Ammonia and Nitrite levels should remain at 0. If you do detect any or both of these in an established tank, it means that you are either overfeeding, you tank is overstocked with fish or your filtration is not adequate. This problem will then have to be identified and corrected.
