I broke it anyway trying to bend the stiff sanitation hose. From there, I ran back for a T and and elbow. I tested it (with water of course) and all seems to work fine. With the deck plate on and the seacock open, the pump quickly clears the tank in a few strokes. With the seacock closed, a pump out should clear the tank through the T. It looked to me like the check valve on the pump was up to it, but the closed seacock should protect the pump? Right?

I'm breaking a lot of rules. I have a bladder(I've had a few over the years, with mixed results), I have no vent line, this Gusher pump may not be the best.

But because we have a harbor pump out boat, the tank rarely holds for long, it should usually be clear. And we have the 3 mil overboard discharge.

I tested it with water today and it all checks out, no leaks and clears the tank in a few easy strokes. Any problems anyone can see?