Using sponges are pretty nice in comparison to the bottle (youshould make a thread for the sponge since there's one for the bottle, copperarabian!!). I tried the bottle method and while it cock-blocked the majority, my filter was just too strong and still managed to push my fish down everytime he got near the flow out from the sides. Plus my fish loved to flare at the back of the walls and he'd get reeeeeeaallllly close to the bottle, which made me very uncomfortable since the edges weren't exactly the smoothest in existance... I ended up sticking a sponge in the tube part, but the one copperarabian provided seems more efficient 'cause you won't have to worry about the sponge possibly getting sucked into the filter like mine, nor will there be debree build up like mine... Woulda did it similar to this one, but I couldn't figure it out! Now I know xD