Dear Peggy, After my first season with my completely re-built holding tank, I have to stop to say thanks a million for the advice you gave me over the last year. Switching from a disasterous, stinking bladder tank that tortured me for the entire last year - I have had an almost incredibly problem-free season. My new tank - a 13 gallon rigid plastic one with dual vents running up to the bow, dual internal dip-tubes, one to the deck pumpout fitting, the other to an emergency emptying pump to the thru-hull, vented loops on the head intake and exhaust, a line filter on the raw water intake, tank-watch warning lights, an inspection port, and used with your KO goop - has worked with absolutely no detectable odor - even when the tank was not pumped out for almost a month at at time. I simply cannot believe it has worked this well. God bless and Good Luck!