I used a bigger bottle (Gatorade) - you could also run both 1/4" tubes independently (don't couple) as inputs to the bottle and a single 1/2" output tube from the bottle to the cage. If you are going that route use an air pump designated for a larger tank (55gal +). I used airstones in the bottle to better disperse the bubblage and wound up setting the whole shebang on a shelf seperate from the enclosures just so none of the vibrations bothered the animals.