Help needed with holding tank

[Robin]

Yes silly me!

The pipe also loops above the waterline too with an anti-syphon so it definitely wouldn't work. Back to the loo pump again!

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[roger]

stainless steel corrosion

Hmmm. I'm wondering about the corrosion mechanism. Fecal matter has an enormous thirst for oxygen (High biological oxygen demand is what the find in fouled rivers.) In a holding tank most of the time I would expect there to be little or no free oxygen unless Headmistresses effective air circulation systems is fitted.
Stainless steel depends for corrosion resistance on an oxide film. Once you lose it the material can disappear very quickly. The same goes for aluminium too - in spades

<hr width=100% size=1>Roger

 

[Anonymous]

Re: stainless steel corrosion

>>Hmmm. I'm wondering about the corrosion mechanism....<<

I don't know, but ss tanks seem to be bad news. Anyone starting from scratch would surely go for a plastic one, no contest?

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[HeadMistress]

Re: stainless steel corrosion

Absolutely no contest!

If I read your comments about a "buffer tank" correctly...it's a recirculating system? Iow, the tank is "charged" with water and chemical that is then recirculated as flush water--along with waste--till the tank is full...then the tank is dumped or pumped out.

If that IS what it is, it's an abomination! There were several such systems sold here in the US in the '70s (when our marine sanitation laws were first enacted), plus some that boat builders tried to save money by "creatively" plumbing a manual toilet to a small tank that either wrapped around the bowl or sat in locker very close to the toilet. By the mid-80s, they'd all been discontinued...with good reason, because they stank, and because watching one's previous "deposits" mixed with chemicals that smell as bad or worse than the waste has -0- aesthetic appeal.

If this is what you have, I'm only a little surprised that any builder is still installing such a system...I say "only a little surprised" because they're obviously doing so only to get out as cheaply as possible. I'd replace it with a proper remote holding tank, plumbed to use clean sea water to flush.



<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987

 

[jfm]

Re: stainless steel corrosion

Yuk!

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[Anonymous]

Re: stainless steel corrosion

>>If I read your comments about a "buffer tank" correctly...it's a recirculating system?<<

There was discussion about this on the liveaboard forum six or nine months ago. Someone explained that some people fit small tanks that can act as a 'buffer' for a few days in a harbour but then have to be pumped out into the sea (i.e. no deck pump-out) which seems to be a very silly way to save a small amount of money. Since most of the cost is the fittings, pipe, tank and pump, why not add the small extra cost of a deck fitting?

Besides, I suspect that if one was in a harbour where these things are rigidly enforced, unless one could show how the tank could be emptied, they'd want the toilet sealed off anyway.

I am very happy with my system which is a Tek Tank, manual Henderson pump, deck fitting, and 1.5" breather. My tank is mostly below the waterline so I can open the outlet and let the seawater come in to rinse it without pumping the water in. I have to pump it out again, of course, but that's quite quick with a 115 litre tank. I would probably have had a slightly bigger tank with hindsight, but it isn't a big issue.

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