The entire boating world has attributed the need for 2 vents in
all holding tanks to me... but I've never said that. That's not the only thing...I see posts all time from people doing who've claimed to follow my advice but done exactly the opposite.
Hey! --I've been repeating that from you for years to everyone who ever asks.
Actually what I think you said, Peggie, was that in sailboats, it's a very good idea to have two, one on each side, since (as you said) the boat spends so much time with wind on the beam that the air flow helps very much in removing stink and aiding aerobic decomposition.
I installed two vents on my tank (which is a rigid rectangle under the V-berth), one each side, each 3/4" PVC (to fit the fitting on the tank) leading immediately beneath the V-berth plywood, laterally towards the hull, ascending outboard almost to the gunwale from where just a short 90-degree bend of 3/4" sani hose connects to the inside of the vent fitting. Rigid PVC tubing = no sags; theoretically complete evacuation of tubing, depending on heel angle. Tank vents = SS through-hull fittings; no screens and so admitting maximum of air.
I tend to advocate a 'complete' periodic flush-out of the holding tank including squirting dockside water down the vent lines before re-emptying the tank. Tends to eliminate places where gook can lodge.
Also I tend to advocate
ONLY nitrator (essentially fertilizer) as a tank additive. In my experience anything perfumed with alcohol-based products just
adds smell rather than eliminating it.
I'll be interested to hear your thoughts, Peggie.