[El Exorcisto]

Every system eventually reaches equilibrium with the elemnts in that system. If you remove a major element like the filter, it will take some time before equilibrium is met again. In that time you'll develop an algae outbreak, maybe green water too. I'd spring for another filter for your cube, or start it up without a filter.

 

[El Exorcisto]

So here is what really confuses me... You are willing to throw a tank out of equilibrium to add a filter to a new tank. You are not however willing to start a new tank without a filter, thus establishing its equilibrium without a filter? Put the tank together, add a couple little powerheads for flow, and be happy. Or, buy a new canister for your new tank, take your pick. Diana, from the sounds of it, he does not have another filter to seed with old media. If he did, I doubt this would even be a question.