Decomisioning Holding tank question

This is an issue we have dealt with since we first bought Sundari. We found that if we use fresh water in the head, it eliminates the smell. I have heard this solution before, but it was only as a result of a failed joker valve that we had to resort to using the fresh water. The head kept losing it's prime. If you have the fresh water capacity, I would recommend trying this. If it works, you could potentially alternate between fresh and salt water when you are underway. Considering the size of your holding tank, would it be possible to split the tank, and plumb the intake into a dedicated fresh water supply in one side of the tank?

[David_Old_Jersey]

I like the idea of using smoke to trace the leak.

As access is restricted to the outside of the tank, what about cutting an access panel (after you have drained it!, and rinsed it ), big enough so you can reach all the problem areas from the inside in order to fix the leak. Might need to borrow a small child

If you are fitting a bladder then you will need to do this anyway.

Cleaning the tank enough to shower in??? Each to their own I guess.........

[GordMay]

1. CLEAN then DISINFECT:
Disinfectants require the removal of soils from a surface before they are effective. Soil and organic matter (like sewerage) rapidly inactivate most disinfectants,
Hence, it’s important to first thoroughly clean the tank;
by physically removing any organic matter (sewerage, etc), so the pathogens are actually contacted by the disinfectant.
A low pressure sprayer (about 200 psi on concrete) is recommended, to ensure that all residual grit and grime is washed away prior to disinfection.

2. Remember Contact Time when disinfecting. Whatever disinfectant you use*, follow the manufacturer’s instructions, including those for minimum contact time. It takes time to kill the pathogens.

* Tri-Sodium Phosphate (TSP), Quaternary Ammonium Chlorides (benzalkonium chloride, etc), or a Phenolic disinfectant are usually preferred over Household Bleach (5.25% active sodium hypochlorite).

[Hi Ho]

I had the same problem for a year and found that the culprit was as Chris C stated in his post, the odor was coming back through the head. When I rebuilt the head I found that while the head was still functioning fine that some of the valves were just starting to deform and were not sealing as tight as they should, after the rebuild the problem went away!

Steve

[Islandmike]

In my food plants Quat is what we always used to disinfect surfaces that will touch any food product. It is very effective.

[Lodesman]

Alan,

You said the problem only happens underway - is there a difference between port and stbd tacks? I wonder if your vents are getting blocked while leaning? There're no elbows or bends in the vent hoses are there?
Also is it blackwater only, or does it hold grey? Would there be any other drains that could burp noxious gasses?

Kevin

[hellosailor]

Wheels-
Akin to smoke...Here's a simpler thing to try. Take a shopvac or other blower and hook it up to blow fresh air into the tank. Now spray or slop soapy water all around the tank. Wherever that leak is, the air coming up from the tank is going to make the soapy water start "blowing bubbles". Usually very obvious to the eye.

If that doesn't work...your leak is someplace below/behind things. The only way left to locate that is with an ultrasonic leak detector, used in the AC industry. You pressurize the tank, and the detector uses a little microphone on a wand to listen for the whistling of high pressure "gas" (i.e. the air) coming out of a fitting someplace. You can often localize the leak, even if it is behind something, that way.

Of course bubbles or smoke would be cheaper. Can you physically disconnect and seal the tank's vent and fill pipes, just to make sure the odor isn't migrating out and then wafting back in somehow??

I would never trust an inaccessible tank to be really cleaned out again, the only way I'd use it would be IF I could get a liner and bladder into it, and just use it to hold the bladder. Even if that means cutting an access port to install the bladder. I've heard of folks installing a tank liner (not in a boat) and then pouring sealant outside the liner, inflating the liner, and using it to "cast in place" as a new sealed lining rather than a bladder tank.


"If you solve the smell of the saltwater going sulferouse, you'll be a rich man. " Problem solved, how come I'm not rich yet?<G>
The seawater doesn't go sulphurous by itself, the sulphur is liberated by anerobic bacteria, same as the stink of low tide on a mudflat. You can stop the smell by running two electrodes into the water and zapping it, producing hydrochlorous (?) acid just like a LectraSan does, with the same result. Kill the critters, and the sulphur doesn't get metabolized. Or drop in a pool chlorine tablet, whatever. Probably simpler to just pump dry, flush with fresh or gray water, and make sure the holding tank is vented though.

Cedar bucket, anyone?<G>

[Amgine]

Old iron tanks used to be treated with a cement wash on the inside to prevent the development of rust in the water, or after a steam treatment to convert them from diesel fuel to water storage. The modern equivalent might be to paint the inside of the tank with epoxy.

One issue I have regularly seen with integral tanks is a severe lack of reasonable access to the inside of the tank. You should be able to see and touch every point inside the tank if at all possible. To do so, one fiberglass/ply integral tank I've seen simply cut very large inspection ports (I could fit my arm and head through it), built a lip in place and bolted the port back down with a gasket.

Did you really say 1000'ish l fresh tank? and this is 2000ish? It might be hard to find a bladder that size, but it likely is the best choice to resolve this problem.

You do know that the smell is from anerobic bacterial activity. When you're talking about a tank of that size you would need a bubbler system, probably combined with a mixer, to prevent it from developing a low-oxygen level at the bottom. I'd talk to a waste-treatment expert, but I think there are micro-sewage treatment systems available so you can find out what kind of schedule would work for your boat (how many minutes of bubbling how often to keep it aerated, etc.)

[Amgine]

Gah. Now I'm fantasizing about having a 1000 l freshwater tank. I currently have the largest tank I've ever had, 53 l, and was feeling rich before this...

[Alan Wheeler]

Amgine, I think 53lts would last my wife one early morning shower ;-)

Lodesman, yeah good points, but I have covered that as well. I cut into the PVC and placed valves on each to lock off all the outlets. Nup. Now removed those valves. By the way, all drains have "S" bends. And the vent outlets are above waterline at all times and vent lines are straight, but do go uphill 3ft to the hull outlets. I don't think the gas is heaveir than air, I imagine it would be lighter if anything and so the rise should be no issue.

One possibility I was also thinking was to have all Grey water go directly out to sea and Black ONLY to the tank. Firstly this would cut down on the amount going into the tank. Secondly I was thinking there is less chance of gas bubling back up through a sink drain somewhere. But I still don't think a sink drain is the issue, although as I am out opf possibilties, I will consider anything possible.
Anyways, my question is, is GreyWater allowed to be discharged at anytime or is it considered under the same rules as black?

[Pblais]

Grey water is fine for direct discharge. You really don't need to haul your morning shower around.

As far as smell, is there any hose involved because once that starts smelling nothing in this world will get rid of it. I just ripped all mine out after it being in place since 1989. It was so bad that with an empty holding tank the whole boat would smell. Now it's perfectly fine again. The smell can penetrate a lot of things given time. Except for hard PVC pipe nothing is really immune to it.

[Alan Wheeler]

The only flexi hose I have is the vent hoses. All others are hard PVC. And there is no smell when at rest, so a leaky hose won't be the problem. The really strange thing is, I thought with having a 32 and a 19mm vent line, the pressure would be so low in the tank it could not possibly come out anywhere else. But it does.

[Chrisc]

Now you have got me interested!
Reading Hellosailor's post do I understand correctly that if I was to tap in a couple of, say 8mm bolts into the side of my holding tank (its a thick wall plastic) and then apply a few amps through them, then the resultant charge would eliminate odours in the tank? If this is so, then that's for me. Much better than messing about with expensive chemicals etc. My holding tank is 75L capacity. How many amps, for how long, at what frequency??

Chris

[Lodesman]

Alan,

The point of my query was whether it was possible the vent hoses were getting plugged with blackwater during a lean? If that was the case, then the built-up pressure might force gas bubbles up through drains, through the s-traps. I think most of the gasses produced are heavier than air, so would tend to settle in the bilge, regardless of their origin.
You're ok pumping grey overboard, except in certain marpol areas - inside the Great Barrier Reef for instance. Chances are the rules will likely get more stringent, so having the ability to tank it, is beneficial. Point was that having sink and shower drains connected to the tank, means more possible gas exits.

K

[senormechanico]

"The seawater doesn't go sulphurous by itself, the sulphur is liberated by anerobic bacteria, same as the stink of low tide on a mudflat."

So "MAN" isn't the only one crapping in the sea??????????

rofl

Steve B.