before I got enlightened to coco I used a powerhead w/aerator in lieu of a diaphragm air pump....
even better; mount the powerhead and return in such a way that it blast the water surface like a faucet....
trust me: this setup is 20X more efficient and reliable than any air pump
if you need more detail, pm me ...I've owed literally dozens if not close to a hundred powerhead, airpumps et et