How do I keep a quarantine tank cycled?

The easiest way is to run a spare sponge filter (or extra filter media in a hang-on-back filter) in one of your display aquariums. Whenever you need to quarantine some fish, move that extra sponge filter or filter media to the hospital tank so it will bring over lots of beneficial bacteria to help purify the water. After the quarantine period is complete, put the sponge filter or filter media back in your main tank. For complete instructions on setting up a quarantine tank, read our full article here.