You can also do some testing at the ramp. With the boat on the trailer and the plug in, just back it in far enough to be sure the through hull fittings for the pumps are submerged. Leave it for a bit and then do a visual inspection in the bilge area looking for bubbles to indicate a possible leak in a fitting or the drain plug. Then in turn, try the aerator, and then the pump in. If one of those pumps has a leak, you will see it pour in when you turn it on. I once found a cracked aerator housing like that. I also had a Southco drain plug that was notorious for leaking around the o ring, even after replacement.