I am sure the Head Mistress will show up soon to add anything that I have missed.
It takes hundreds of pumps to fill the tank with our Raritan PH-II manual head but we have an electric water.html" target="_blank">raw-IRJDSUNE9932123321222xxeww-water deck wash system so we can fill through one or both of the 1" vent hoses which terminate in mushroom through-hull fittings high up.
Put the water
into the tank via the deck
pumpout fitting which sends the water into the tank at the bottom to stir up any sludge so it can be pumped or dumped out.
Those cheesy standard screened 1/2" vent fittings are too small and you can't backflush like this with them.
You can if you knock the screen
out, which you should anyway to improve air exchange with the gasses in the tank. You'll never have a vent blockage if you backflush it every time you wash the boat
If you're flushing
out the tank, you'll have to restart with K.O. anyway, and besides, toilets designed to use pressurized fresh water use chlorinated water from their tanks
...so there's no reason not to use chlorinated fresh water flush out the tank. The water in most marinas
is anything BUT clean due to run off, so I wouldn't use the washdown pump
at the dock
...I'd get out at least a 100 yds (or far enough away from people that might think you're dumping your tank) and then just let the water run after you start the macerator to rinse out the tank. And you really should should flush the sludge out of the bottom at least 2-3x/season and especially in preparation for any winter or other extended layup
....sea water is fine and you don't need to fill the tank. Just put about 6" into the tank via the deck
pumpout fitting and turn on the macerator, letting it run till you see only clean water.