Sounds like you got some crap growing in your tank. Fairly common. Hit it with some Clorox and flush with freshwater. Every once in a while mine gets a little funky and the bleach does the trick. You can also buy stuff at worstmarine that will solve the problem.
Nope no anode. I treat the water too. I tried a couple brands of water treatment, with no success. My guess is that it's just a cheap tank liner. I will just replace it with a marine unit. Gene Dugan Boca Raton, Fl. "Nauti Marie" 1989 33 FBC 2007 8.1 Crusaders
