If they work for a week or so, then its not the pump. Make sure your lines are also not crimped. Do they all do this? they all work good for a week then stop? maybe some one can advise you on some good airstones. You could also run an extension cable and propping the pumps up above the water line cant be that difficult, they can mount to a wall(there should be a hole for a screw or hook in the rubber base.