Originally Posted by dlsrks
Good idea but don't think it would be enough. Thank for the idea though. May use water from my 75 gallon tank.
This is what I do for my 20g QT, I take a powerhead, water bottle, piece of sponge from my display tank, and some filter floss. I cut half of the bottom of the bottle off about 1" up from the bottom. I push the sponge and filter floss into the bottle (you can put carbon between the two if you like as long as your not treating with copper) and then put the bottle on the powerhead, they usually fit perfect. Then I place it in the tank and turn it on. This will give the tank a mechanical and biological filter as well as flow. Obviously, the bigger the tank the bigger the powerhead and bottle need to be. I have done this many times and it works great.
One thing to keep in mind, if you have small fish use a soldering iron and poke holes in the bottom or face the opening towards the glass so small fish do not get sucked into the bottle. I only had this happen once but its worth noting.