You don't need to recycle. You're just changing the water, and having a clean up. You're still preserving filter media and bacteria on solid surfaces within the tank. Take it from me, there are enough bacteria in a big Fluval internal filter to keep ammonia at bay.
If a disease has been present and treated for, and the tank bleached afterwards you need to precycle the tank. But remember I usually keep some cheapo live rock in there so there's my 'bacteria in a bag'. |