Holding Tanks - Poly or Stainless???

[HBBurlington]

We are new CS owners...and would like objective feedback about holding tanks.
Stainless?
Poly?
Pro's and con's, please??

I just don't want "that smell" when we board....
Oh yeah... and only "#1" will be involved.

Thanks!!!!

[IslanderGuy]

I do not know about the pros and cons too much, but I believe "the smell" is usually from the hoses or due to a clogged vent, not coming through the tank walls themselves. I do not think the tank material matters all that much in regards to smell.

[arf145]

Smell will permeate bladders, but I have high hopes for the poly tank I put in a year ago. So far so good. I haven't read of anyone reporting good plastic tanks getting permeated. Hoses are definitely an offender--get the good ones.

[Minnewaska]

If you can, go with Stainless, but that isn't absolutely necessary. What is absolutely necessary is the largest vent line you can manage. Then, never put any chemicals of any kind in the tank. No deodorants, bleach, soap, nothing. You need good bacteria to break down the stuff and that will over run the smelly bacteria. Any chemicals kill the good bacteria. Also, very important is to flush enough water (fresh or salt) to push all the waste to the tank. This is the typical cause of smells that permeate the waste lines.

[Jeff_H]

Do not use stainless steel for holding tanks since the acids eat them up quite quickly and besides the heavy plastic tanks are less likely to transmit smells and are quieter.

Jeff

[turbulicity]

I second Minnewaska, except the stainless choice. I don't know about the merits of stainless over polyethylene for holding tank application. Whichever you go with, make sure you get a strong tank that can withstand the vacuum from dock pump-out. Seamless pure polyethylene of 3/8" thickness would be my choice.

Odor, as others pointed out, can be prevented by:
- Good quality sanitation hoses. Make sure there are no sags and low points in the lines where waste could stand in the hose.
- Good ventilation inside the holding tank. You want aerobic bacteria to overrun the unaerobic ones.
- Flushing with sea water will cause a smell in the head. If you have a choice, flush with fresh water at least before leaving the boat for a while. Pump enough flushing water to rinse the hoses completely.

[SVCarolena]

Originally Posted by Jeff_H

Do not use stainless steel for holding tanks since the acids eat them up quite quickly and besides the heavy plastic tanks are less likely to transmit smells and are quieter.

Jeff

I was just about to type the same thing. Go with poly - no worries about crevice corossion and is cheaper than stainless; use the best hose you can find (Trident or Sealand Odorsafe); and install a t at the sink thru-hull so that you have the option of flushing with raw water or fresh from the sink by closing the thru-hull. If you do the last flush of the day/weekend with fresh prior to leaving the boat it will prevent a lot of smells that come from all the stuff living in the raw water. Google "Peggy Hall" - she is the expert on boat odors and heads, and has a great book on the topic. She also frequents some of the boating forums.

[LandLocked66c]

Or go composting head. Why isn't this an option?

[Omatako]

There are some earlier threads on this board about using solid PVC piping (domestic plumbing) to pipe up heads and those members have had really good results.

That's where I'm heading because I have had enough off bad smells so it plastic thick-wall tanks and solid PVC plumbing wherever possible. as far as I'm concerned even the very best, most expensive, sanitation-grade flexible tubing is all rubbish.

[chef2sail]

Stainless....are you kidding. Go pee on some and come back a few days later and see what it looks like. Acid etched.

Poly is the way to go. NO seams...

Good quality lines like Trident green stripe. Fresh water if possible. Good bacteria eat up the smell. Large vents like Minne said help.

We completely redid ours last year and oh what a difference...