A great, and cheap, QT filter is a simple sponge filter. Put the new sponge somewhere in your main system for a few days and transfer it to the QT-almost instant cycle. Never put the sponge back into the main system, of course. Just toss the sponge, or boil it, if you need to. But, if you ghost feed the QT, you should always be okay. Algae is fine in your QT, but the darker you keep new arrivals, the better.