Probably ought to be in the noobs forum but here I am because it's air pump talk. Are pumps rated in liters per hour or some such? What about related accessories such as stones and ornaments? Is there some way to match them to ensure adequate air supply and proper functioning of the peripherals? Also how are they rated for the depth to which they can pump air? Atmospheres or millibars or something? And if so how does that translate to the real world? I'll hang up and listen, thanks.