I’ve had a lot of trouble with my ac pumps for some reason, maybe it’s the heavily silted water in Charleston. I’m on my 3rd pump in three years! Three years ago I replaced the pump that the boat came with, it worked for the two years we owned the boat plus however many with the po. I replaced it with a Koolair ceramic shaft, water cooled pump that lasted two seasons then died. I replaced that with the little giant(ac manufactures suggested pump) which lasted 6 weeks! I now have a march/dometic ceramic shaft, water cooled pump. We’ll see how long that lasts.
There’s nothing fancy about my install, I have a groko strainer, the pump is below the waterline, and the head is about 4 feet. I’m using 500 gph pumps as suggested by the ac manufacturer.