I've had a hell of a time easily finding a pump. My biggest challenge has been the lack of adequate documentation on packaging in the stores and even to the extent of poorly detailed specifications online by the various manufacturers which then reflects in the information also lacking at the reseller level. For instance, one of the dominant pump makers that supplies Petco & PetSmart tells you that the pump will serve 10, 20, 50, 100 etc. gallon aquarium tanks. No mention of the air flow rate, nor is it adjustable on the pumps. Of course the help in these stores don't have the in depth knowledge to bridge the gap.
Dennis and perhaps other may disagree with me but I would've have been more than happy to pay Dennis more for the convenience of a "complete solution" that included a suitable pump and an appropriate length of silicone hose. Even so, I'm betting that Dennis choose not to do this thinking that we would rather have the ability to completely customize the solution to our own specific need/desire.
Maybe this is an issue in only the U.S. since we aren't on the metric standard? Clearly I need to do a little bit more research online to try to find a pump that fits the need, but I've been distracted by other things and will get to this later.