Other than putting in a filter that is easy to change, I don't have any other ideas of how to avoid this in the future.
Cleaning out the sump a bit more often than every 25 years is one way...and there is a way to do that without the need for any manual labor:
Raritan only markets their "C.P. Cleans Potties" as a bowl cleaner--and it is an excellent one. But it's also the best sump and drain cleaner on the planet. C.P. is a bio-enzymatic cleaner that not only destroys odor on contact, but the enzymes in it "eat" (euphemistic term) hair, soap scum, body oils, galley grease and all the stuff that clogs sumps and drains and makes 'em stinky. All you need to is put 2-3 oz down the shower drain into a sump that's about 1/3 full of clean water...turn on the pump to get it into the hoses...when it can stand at least overnight...the enzymes need time to work. Then flush clean water through the sump, pump and hoses. You can even let it remain in the sump for weeks, 'cuz although the enzymes exhaust themselves in 24 hours, there's nothing in C.P. that can harm anything.
To clean sink drains, close the seacock, then put about an ounce of C.P down the drain and fill the drain with water--again when it can stand at least overnight. The next morning (or whenever) open the seacock and flush with plenty of clean fresh water. That's it. Depending on how often and how long you're on the boat, about every six months is about as often as necessary. If it's the first cleaning in years, new hoses and more than one application may be needed.
--Peggie
(These instructions are for the typical shower sump and sink drains. If your sumps are larger, and have longer hoses or multiple hoses, you may need to use a bit more C.P.)
--Peggie