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sooty1957
sooty1957

Posted: Sat Sep 20, 2008 9:20pm

Post Subject: decommisioning a pump out tank

I am thinking of fitting a thetford cassette toilet to replace the pump out one. What would be the best way to decommission the tank before capping it off? (ps it is not removable) Thankyou Steve

Tony-B
Tony-B

Posted: Sun Sep 21, 2008 1:15pm

Post Subject: decommisioning a pump out tank

Dear Steve, After you have pumped out the tanks there is probably a half inch or more of liquid in the bottom plus the paper and solid matter that has not yet decomposed. If you are using blue then there is likely to be more solid matter because you are actively preserving it an killing the microbes that decompose it. If you are not using blue I would pump the tank out, add about 3 inches of water plus one of the microbe feeding additives. Leave this in for the summer and then pump it out, flushing with lots of water. With a bit of luck all the paper and solids would have decomposed by then so the residue could be pumped out via the old "toilet hole". If you are using blue I think I would pay a boatyard to do it because I think it will need a pressure washer all around the tank and lots of pumping & flushing. After that is done it will probably still need the remaining liquid pumped out via the toilet hole. Tony Brooks

sooty1957
sooty1957

Posted: Wed Sep 24, 2008 10:48pm

Post Subject: decommisioning a pump out tank

Once again thankyou for your help, and all points noted. NOT quite sure what to do now ! Is there an alternative to using 'Blue' for better results?

Tony-B
Tony-B

Posted: Thu Sep 25, 2008 9:53am

Post Subject: decommisioning a pump out tank

Dear Steve, Whilst blue may have had a place in the original Elsan bucket type facilities (a real tall bucket with a a seat on top and the contents on open view) I just wish people with holding tanks would look into things a bit more fully. The raw contents contain two types of bacteria. Anaerobic that work without oxygen and decompose the paper & solids producing smelly gasses and aerobic that need oxygen to work and produce no or very little smell. Unfortunately the anaerobic ones seem far stronger. Blue normally contains "perfume", colouring agents and formaldehyde that kills bacteria to " and thus preserve the turd" but unfortunately after a certain degree of dilution the anaerobic bacteria seem to be able to thrive so we get that awful toilet smell. To prevent the smell we need to encourage the aerobic bacteria to thrive. I suspect the majority of boast have a single breather (if any) on their holding tank and it is often far too small. In my view you should have two breathers at opposite ends of the tank with each being well over an inch in diameter. This will allow a free flow of air over the effluent so there is always plenty of oxygen in there and the movement of the boat etc. tends to help the effluent absorb it. This allows the aerobic bacteria to thrive so the bacteria decompose the waste with little smell. Once you have an adequate supply of air you can help the bacteria by adding an additive that contains chemicals to help feed them and also oxygen. This does not have to come from marine sources - B&Q sell stuff for smelly domestic septic tanks. The tank on JennyB only had a 3/8" breather and that was full of spider webs so there as a terrible smell problem. Having researched the subject I fitted a 28mm breather at the opposite end of the tank and because of the small existing breather, that was not easy to improve, I made up a metal box with a 12v computer fan inside and fitted it to the 28mm breather. The fan is controlled by a pneumatic push button light switch located by the toilet. If you push it before you start (I have adjusted it to a 20 minute "on" period) when you open the flap air tends to get drawn down into the toilet rather than the "deposit" displacing air out of the toilet. I use no blue, but do occasionally add one of the additives described above. The toilet rarely smells and the only time I get comments is when we moor close to a boat with a vacuum or macerator toilet with a virtually sealed tank and they operate it. You ask what to do. If the tank is leaking or you simply want to get away from pump outs then as I said, get a yard to pressure wash the tank as best as they can and pump it out etc. If the problem is smell then fit one or two large breathers and forget Blue. I use very little, some people throw yeast tablets in and others follow the instructions on the additive bottle. A fan in one breather is even better. I know many are sceptical about all this but the invitation to see (and smell) it for yourself on JennyB is open to anyone who cares to arrange it directly with me. The boat is in the Braunston area. Tony Brooks

sooty1957
sooty1957

Posted: Tue Sep 30, 2008 8:33pm

Post Subject: decommisioning a pump out tank

Thankyou, a bit late getting back, but I found that very interesting. Steve

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