It's a common problem in most boats. [FONT="]Sewage—all organic material--contains both aerobic (needs oxygen) and anaerobic bacteria (functions in the absence of oxygen); but only the anaerobic bacteria produce foul-smelling gasses! Both aerobic and anaerobic bacteria break down organic matter, but when organic matter breaks down aerobically, it converts to CO2, which is an odorless gas, and water. So, as long as there is a sufficient supply of oxygen to the tank, and an aerobic treatment is added to aid that which naturally occurs in sewage, the aerobic bacteria thrive and overpower the anaerobic bacteria, and the system cannot produce odor.
[/FONT] [FONT="]So the key to odor control in most tanks is the vent line; it must allow a free exchange of fresh air with the carbon dioxide generated by the sewage. Boat builders, boat owners and boat yard personnel who install holding tanks have always viewed the vent line only as a source of enough air to allow the tank to be pumped out without collapsing and as an exhaust for methane (many even mistakenly believe that methane—which in fact is odorless—to be the source of odor.). Some take the attitude that tanks must inevitably stink, so the thing to do is run that vent line as far from people areas—cockpits, sun decks, etc.—as possible, or make the line as small as possible, or install a filter in it. All of the above actually create the very problem you want to solve.
[FONT="]If you'd like to send me a p[FONT="]rivate message [/FONT]I'll be glad [FONT="]to [FONT="]help you sort out the specifics of what you need to do to modify the [FONT="]tank venting to [/FONT]increase the amount [FONT="]of air exchange needed to c[FONT="]reate the [FONT="]a[/FONT]erobic conditions in the tank[FONT="] [FONT="]needed to prevent [FONT="]odor. Fwiw, it[FONT="] was the desperate need to solve exactly the same problem on my first [FONT="]boat with a holding tank that [FONT="]started me on t[FONT="]he path to a career in marine [FONT="]san[FONT="]itation [FONT="]30 years ago.
[FONT="]Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein[/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][FONT="]
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