Wayne wrote... > The installation (its original) of this tank has two outlets, one for > a deck pump-out and one for direct pump-out at sea, i.e., no Y-Valve here. As I replied to his private email, "Well now I have to admit that you got me with that one. A shutoff valve installed IN THE tank discharge is indeed a good idea in that case. And I like putting two discharge fittings in a tank because it does eliminate a y-valve. Installing all fittings in the top of the tank, with pickup tubes inside the tank on discharge fittings is an even better idea, though, because it eliminates standing waste in all lines...but that's not always possible because it requires at least 5" clearance above the top of the tank. It's a very easy mod to make if you do have the space to do it. Randy said... > ...when we replaced our holding tank, the yard that did the > work told me that the tank mfgr. Stated that they wouldn't install two 1-1/2" > vents because it was against CG regs. Personally, I think this is a huge load > of BS. It's a huge load of BS. The CG only requires that waste tank vents be an adequate size (whatever THAT may mean) and exit the hull. Who was the tank mfr? 'Cuz I suspect the BS didn't originate with them, but with the yard. And btw...Teeing vent lines together doesn't work very well 'cuz air tends to just travel across the top of the tee instead through the tank. Dick Brunson said... > Dometic Sanitation has a product called "Tank Saver" This thing: http://www.sealandtechnology.com/productpages.asp?pid=68 I don't like 'em, 'cuz too many of the people who have 'em think it relieves 'em of the need for ANY tank vent maintenance--that it protects the tank from EXplosion as well as from IMplosion...and learn the hard way that it doesn't. Saving fools from themselves is mostly an exercise in futility! John wrote... > I am contemplating > installing an ElectroSan treatment system to support the (2) heads on > board our boat. My question is: What happens to the holding tank after > the installation? Obviously I would need to keep the holding tank > intact for the times we are in 'no-discharge' zones. Does this mean > that I should, presuming I have installed a mushroom style tank vent, > apply a quick shot with the hose every time I wash the boat? I would...dirt daubers, dust, pollen, spiders don't know whether you're using the tank or not...and the last thing you need to discover when you have to use the tank is a blocked vent. > I would > think that some level of water in the tank would not be a bad thing as > it would keep the residual coating of 'stuff' inside the tank from > drying and potentially creating additional problems. Flushing out the tank is the right way to prevent that problem. But in the short term, an inch or two of water in the tank isn't a bad idea. > I presume > that the plumbing would be from the head to the ElectroSan then y-valve > the output of the ElectroSan to either go over-board or to the holding > tank. It doesn't matter whether waste going into the tank has been treated first or not...'cuz once it does go into a tank it's no longer "treated" waste, so you couldn't legally dump the tank inside the "3 mile limit. Nor does treating waste before it goes into a tank help reduce odor...'cuz if even ONE li'l ol bacterium survives, it'll quickly multiply into zillions again, putting the tank contents right back into the same condition they were when they left the toilet. So put the y-valve where it's most accessible. The heads are Tecma 24v freshwater versions. In which case, I'd go with the PuraSan, which was designed for use in fresh water (although it works equally well in salt water) instead of the ElectroScan, which needs salt. http://www.raritaneng.com/products/waste_treatment/purasan.html -- Peggie ---------- Peggie Hall Specializing in marine sanitation since 1987 Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and Other Sources of Aggravation and Odor" http://shop.sailboatowners.com/prod.php?51996