Plain ol' liquid detergent...
All laundry detergents and dishwashing liquids (also detergent) are biodegradable--which, btw, is a meaningless term that is NOT synomymous with environmentally friendly...although laundry and dishwashing detergents are.Lysol won't work. Neither will anything else used so sparingly it can be mopped up with paper towels in an area as large as a bilge. But a thorough cleaning with plenty of detergent and water, followed by hosing ALL the dirty water out will. I dunno why so many people think that all you have to do have a clean bilge is just dump in some cleaning product, slosh it around and turn on the bilge pumps. You wouldn't just dump something into a bathtub or kitchen sink full of dirty water, agitate it a bit, then just pull the plug and expect the tub or sink to be clean...so why would anything expect a clean bilge if that's all you do?To Ivan's and Mike's credit, that's not what they suggested, but it's what so many people do to clean a bilge that I had to discuss it.Mike, rinsing the bilge out with sea water just restarts the same "primordial soup" you just flushed out. If you'll use only fresh water, you'll find that you won't have clean your bilge nearly as often. In fact, if you do a VERY thorough job of both cleaning and rinsing it out with clean fresh water, you shouldn't have to clean your bilge more than once--maybe twice a year.Btw...sumps are another source of odor. They need cleaning too.