Me, I've always used a turkey baster. I either make a pond or put something like a piece of pvc through the false bottom and cover the top so frogs don't get in there. I'll try to get a better pic leter if you want but this is what I'm talking about...
My drain point is in the front left corner (black vertical pipe) and covered by a piece of slate rock. If I have to drain I move the rock and stick a turkey baster down there to suck up the water. Plus it kinda blends in.