Originally Posted by Minnewaska
I don't believe the space between the bottom of the bowl and the pump, which in our case is a macerator, is ever fully empty. A dip in the line is going to permeate eventually. l would rather leave an inch of clean water in the bowl if this was an issue.
That space below the bowl is the easiest to insure has clean water in it, especially when away for a few days and we flush a couple of bowls of fresh water from the sink, instead of sea water.
Well, a pool of fresh (or sea water) filling the hose would block the holding tank gas without the permeation issue. So a long flush would be best. But if there is no dip, in other words, the hose slopes downward all the way to the holding tank, my experience is you can't keep an inch of clean water in the bowl. It all drains down to the tank. At least it did with our old Jabsco head, and I believe it does with the Raritan PHII I just installed. I have no dip, so the bowl drains.
I'm just suggesting to be prepared for this. I have no macerator, so not sure of its impact on this.