Q&A for How to Cycle a Fish Tank

You're basically establishing the nitrogen cycle in the tank. Ammonia is toxic and it will kill fish. It'll actually kill anything in the water. So you need to get rid of it and reestablish the nitrogen levels. That's the point of cycling the tank.

No, you can run a fishless cycle. A lot of people actually prefer fishless cycles since you don't need to worry about harming your fish in the process.

You can intentionally put ammonia in the tank without worrying about killing your fish. That's what moves the process along so fast.

Yes! Dwarf frogs are even more sensitive to water quality than most fish. Complete a fishless cycle prior to adding any frogs to your aquarium.

You can't cycle bowls, as they usually don't have filters, or have inadequate filters. Bowls are not good for fish, so buy a real tank.

If you don't do something that kills the good bacteria, you will only need to cycle once. Some things that can kill the good bacteria are: chlorinated water, cleaning the filter media with tap water, the filter not running long enough, etc.

I would put the filter media into a bucket with water from the tank. Move that immediately and set up the new tank as quickly as you can. Keep as much water from the old tank as you can as well, at least 40%. Do not let the filter media dry out or come into contact with untreated tap water. Both of those things will only kill the bacteria you already have.

Do a fish-less cycle and then add one goldfish at a time a week or two apart. Another option is to have a large aquarium with one goldfish, feed it sparingly, and do 20% water changes every couple of days. Lots of plants will reduce any stress on fish during a fish-in-tank cycle.

Once every other day, just as you would if there were fish in it. You don't want to add too much too often because this can cause your ammonia levels to spike.

Yes, you can use other fish foods. However, using pure ammonia works much better. If you decide to use ammonia, be sure that it has no scents or cleaning soaps in it, as this will not work for cycling.

There's a lot of mixed information, but it all comes down to the personality of the fish. Some guppies are known to nip at the fins of slower bettas, but some bettas may also mistake guppies for bettas and attack them due to their bright colous. Try it out and see how it goes, but have a spare tank close by in case you need to separate anyone.

Try Ace Hardware. Get the "Janitorial Strength" ammonia. If you find what says to be "pure ammonia" elsewhere, make sure that you read the ingredients on the bottle and shake the bottle-- if it suds up, you DON'T want it! Dr. Tim's has Ammonium Chloride for cycling as well, though you have to buy it online.

The only mandatory step is adding the biological filter media. Adding the gravel/other substrate may prove helpful, as the beneficial bacteria will colonize in the gravel as well, but the largest, most important colony will always be in the bio filter media since it has a constant flow of waste-dense water coming into contact with it. The colonies that may form in the gravel and on the decor will be minuscule and will not make a noticeable difference during the initial cycling process. Adding an additional carbon filter may prove helpful in removing toxins in the water, however it is not required for establishing a main cycle.

You should wait at least a week so the good bacteria can establish their colonies in the filter, but to speed the process along, place bacteria bloom into the tank. If you do that, you can add the fish to the tank in about 24-48 hours.

It can take four to six weeks, but you can kick-start the progress by adding mysis or brine shrimp into it. Or, you can buy a bottle of beneficial bacteria and add the recommended amount.

The beneficial bacteria that was with the water that you drained is gone. Although, if you keep the filter that was in your cycled tank, the beneficial bacteria in the filter media will remain. Just be sure not to wash the filter media with tap water, it'll indefinitely wipe out the contents. You will have to repeat the process all over again, but this time it will take less time to cycle, approximately 2-3 weeks.

If it's not cycled at all, then cycle it. If it is, then add just one or two fish at a time (depending on size of fish and the size of the tank). Make sure you wait a week or two between adding fish in order to let the tank complete mini cycles. Add plants and snails (research snails first to make sure you get appropriate ones) to further reduce ammonia and nitrates.

It will take 4-6 weeks, but you can speed the process up by adding filter media from an established tank.

No, you should use tap water with a water conditioner to fill your tank and use hot tap water to clean you decorations.

Absolutely. Shrimp are very sensitive to toxins like ammonia and nitrite, and even excesses of nitrate.

Using distilled water in your fish tank is not a good idea. The fish need trace minerals from non-distilled water to survive.

Adding old water will have little if any effect on speeding a cycle, as the main colony of bacteria is in the biological filter and not in the water column. You can, however, speed up the process by adding the bio filter from an old tank as a way to help seed the tank with bacteria.

If you have fish in the tank, you probably have too many. Those water changes are also way too much. Instead, try 25%. You want ammonia to build up enough to culture the bacteria, but low enough to keep fish alive. It sounds like you don't have a filter though if there are zero nitrites yet. Get a filter and do the cycle correctly.

If you are seeing nitrites increase, then you are doing ok. Keep those in check with 20% water changes every few days. Once you see nitrates rise, the tank is nearing being cycled and water changes can be reduced until all nitrites and ammonia are gone or at very low levels. Then just monitor nitrates and do water changes every week or so until you get a routine down. Add plants and snails (research these first though to make sure you get the right ones) to further reduce nitrates. Good luck!

Invertebrates tend to be less resistant to ammonia/nitrite levels out of their range (0 ppm is the best). It is ideal to add them later, when your cycle has been established.

It is best not to clean the filter unless there is a lot of organic buildup. You want to have a buildup of beneficial bacteria, and cleaning the filter regularly will slow that process. If you see chunks of food or matter in the filter, however, it is okay to take those out. If you see a lot of grimy buildup on your filter cartridge otherwise, you can lightly rub the cartridge in dechlorinated water to clean it. Do not use untreated water.

Try separating the frogs and sucker fish and see if the frogs health improve. Make sure your other tank is also cycled.

Depends on the type of cichlids. Many South American cichlids could, but most African cichlids probably wouldn't.

Yes, but you can slow down on the changes to a steady week or so. However, the amount of changes should be done if your fish are not sick.

If you are only performing water changes every 2 months, you should not have an aquarium. Depending on the size of a tank (smaller tanks absolutely need water changes once a week), water changes should be performed at a minimum of once every 2 weeks. Weekly water changes are really preferred. That said, the nitrite/nitrate cycle only occurs once, unless you do something to kill all of the bacteria.