Jim, it would take a week for enough water to backfill through a macerator pump--especially one that's above the tank--to even start to rinse it out.
The sludge seems to eat all of the seals in the Jabco, and the brass screws that hold it together. You need to find a way to clean after use. Maybe Peggy will chime in with a definite pronouncement.
Sailem8, I can't imagine what you could possibly have done to a SeaLand T-Pump that could destroy it in just a year!
Holding tanks, like everything else on a boat, require maintenance. There shouldn't be an accumulation of sludge in a tank deep enough to damage a pump. I've posted instructions for flushing the sludge out of the tank at least half a dozen times...and I've included 'em in my book. It doesn't need to be done after every use, but it should be done at least 2-3x/season, every 2-3 months if you sail year round, and especially in preparation for winter or any other extended layup...and it needs to include rinsing out the overboard discharge pump and plumbing. Here they are one last time:
Pump out the tank, or dump it at sea. Then put enough water into the tank via the deck pumpout--'cuz that sends the water into the tank at the bottom to stir up any sludge and hold it in suspension so it can be pumped out--to cover the bottom to a depth of 4-6"...it can be fresh water at the dock or sea water using a washdown pump. Pump out or dump...repeat...repeat...repeat...till you're pumping or dumping clean water. If you're doing it at the pumpout dock, then do it one more time with the overboard discharge pump running. If you're doing it offshore using the washdown pump, just let the water keep running while you dump the tank. Quit when you're dumping clean water. Tank products like No-Flex Digester help to keep sludge at a minimum.
Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
