Hi all Believe it or not I still run a otto internal filter in my 4 ft tank with 8 juvies ranging in size from 1 1/2 to 2 1/2 inches in size, while I have no problems with ammonia etc or illnesses I would like to upgrade to a canister filter as they are getting a lot bigger. Can I just add this to the tank as is with my other filter running as well and how long should I leave the internal in for while I do this Thanks guys

Leanne