Step One: Cycling

If you ask a pet store employee if you can have fish right away after setting up a tank, a good employee will tell you yes. A nice fish lover will tell you that you need to cycle the tank, or you will be coming back to get more doomed fish soon.

The cycle is when an aquarium is readied to support life. An newly setup aquarium is incapable of supporting any kind of life, as it does not have the correct bacteria and such in place to convert waste into less harmful forms. This change is a constant cycle in an aquarium, but the first time is the important one.

There are two ways to cycle a tank. Most other ways are just variations on these two. The first is fishless cycling, and the second is cycling with fish.

Fishless Cycling

Materials:

Time: From 9 days-3 weeks

The first step is to add ammonia to the tank. Add enough that the test kit measures ~ 5 ppm. Remember how much you had to add to get that amount, as ammonia comes in very different concentrations. Add the same amount every day. After 3-4 days begin testing for Nitrite, but continue adding Ammonia.

When nitrite appears wait for it to spike, i.e. no Ammonia 24 hours after adding it, but tons of Nitrite. Cut the Ammonia dosage by half and begin testing for Nitrate. It takes longer for Nitrate to appear than Nitrite. When Nitrate appears Nitrite should disappear.

After you have Nitrate, test carefully to make sure all Ammonia you add gets converted, then do a massive water change with properly treated water. (Treated water is water with a de-chlorinator added so that you will not lose the effort you just made due to chlorine or chloramine in tap water. ) Now add fish. You can normally nearly fully stock the fish tank now that it is cycled, just stop adding ammonia when you add fish, and make sure there is no ammonia or nitrite present before you add them.

Cycling with Fish (Traditional Cycling)

Materials:

Time: 4-6 weeks

Add several fish you do not care for, as they will often be very damaged by the cycling. Common choices are danios, or feeder goldfish.

Test the water, and when Ammonia begins to appear, start your water changes. You want to keep the ammonia as low as possible, because ammonia kills fish. The main reason this method takes so long is the water changes that continue to dilute the ammonia and keep the fish alive. The water will slowly go through the same cycle as in Fishless, but don't forget that Nitrite is also very poisonous to fish, and that level needs to be kept very low as well.

Once you get Nitrate, your cycle is done. Do a large water change to lower the Nitrate level. Now you can return the fish you used to cycle, and get only as many fish as you returned. Or you can add a few fish every few weeks because the bacteria only grew enough to process so much fish waste, so more than its expected amount would just start the cycle again.

Links to other Fishless Cycling articles...

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