Holding tank tube elevation

[Flyfisher22]

I had my new R27 holing tankpumped out for the first time and noticed a few inches remaining in the tank. Is this normal? The service said it depends on the elevation of the pump out tube.

 

[Admiral S]

I confirm the same result. The pump out hose and fitting is slightly elevated in the bottom left of the tank when looking aft.. This allows air to be sucked up and breaking the vacuum. We combat this by filling the tank with fresh water after pumping out. We pump again, and sometimes go for a third round. This has been working well for us the last few weeks.

 

[baz]

Yes.... back flushing with water one or two times after a pump out is the general rule for getting the tank's bottom sucked out. You don't have to fill the complete tank with new water... just enough to get the suction going again. I also will rock the boat back and forth (side to side) after loading some fresh water into the holding tank to get things sloshed around in the tank's lower section.