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Holding tank stinks.-gctid816983

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    Holding tank stinks.-gctid816983

    When we flush the heads the holding tank gas from the outside vent emits really bad odor. What is the solution.
    Tim Wing
    The Betty Jean

    There are a few. One that I know of is a special filter that goes in the vent line. Another is to add an enzyme solution to the tank. I'm not sure which works best, but they all claim to. There's always the rinse and pump, repeat, repeat, repeat.
    P/C Pete
    Edmonds Yacht Club (Commodore 1993)
    1988 3818 "GLAUBEN”
    Hino EH700 175 Onan MDKD Genset
    MMSI 367770440


      Use a chemical in your holding tank that contains formaldehyde. It will kill the bacteria that creates the smell. Been using it for years in RVs and boat holding tanks.
      Started boating 1965
      Bayliners owned: 26 Victoria, 28 Bounty, 32, 38, and 47 since 1996



        Check it out


          Some claim NoFlex digester works and a carbon filter in the tank vent line. It didn't work for me. I found the blue rv tank treatment and frequent flushing of the tank works best.
          "Martini's Law" SOLD
          1986 Bayliner 3270, 110 Hino's
          Nova Scotia, Canada


            I've had the best luck with Noflex but it takes about 10 days at the beginning of the season to start working. I also have the filter on the air line. If you ever over fill the holding tank, that filter will get wet and become usless. You can pay 50 bucks for a new one or cut em open and replace the innards with the charcoal they use in aquarium filters ( get it at a parts store).
            Hanging Loose
            98 Carver 350 Mariner
            KRUSTY KRAB
            2001 305
            5.7 BII


              I've been using 'NoFlex' for about 5 years now and had good results.
              Midnight Star
              1996 3587
              Twin diesels, Hino 250's
              Ladysmith, BC
              History: 1996 - 2655, 2001 - 2855, 1984 - 3270


                Big Orange Filter

                works great no more stinky boat for me

                [img ][/img]


                  NoFlex sure worked for us

                  Can not believe the difference it has made but may get a big orange as extra insurance

                  Where do you install it ?


                    Venting and Norlflex are the best approaches.

                    As for filters we build simple ones using regular 2" PVC pipe and activated charcoal available at Walmart for fish filters ($5/can)

                    You get to make a larger higher capacity filter that can be refilled when needed and has little cost.

                    "Where do you install it ?"

                    On the vent line between the tank and the outside vent.

                    Look under your stb side bar sink - on the wall inside the lower cabinet there is a false panel, take it off and you will see the vent line in there.
                    Northport NY


                      A friend taught me a good habit when pumping out. Pump out the tank. Fill it about 1/4 with fresh water (there's usually a fresh water hose near the pumpout). Pump out again. Fill 1/4 again with fresh water then pump out a final time. After about three times we have eliminated the smells when flushing.


                        Further to smitty's comments. I added a Holding Tank Vent Filter (HTVF) in the bar cupboard per the attached photo. It is secured by velcro straps and is easily removed to refresh the activated carbon.

                        Here are the instructions for building this, which I saved some time ago from this site. I can no longer remember who posted them orginally but they worked great and thanks are due!

                        QUOTE:So you are wondering what a HTVF is right? Well you know that unpleasant stench you sometimes get from the vent on your holding tank? Normally it happens when you least want it and this little device already proven to work extremely well as it can be purchased at West Marine for the ridiculous amount of $104


                        Only problem is it lasts about a year and then needs to be replaced for the much cheaper price of $94 since you keep the fittings on the end and only replace the center cartridge. How nice of them!! In reality, it is only a tube with Activated carbon in it which absorbs the odour.

                        You will need to purchase the following.

                        From Home Depot or any hardware store

                        A 12" length of 2" abs plumbing pipe

                        (here I had to by a 3, length @ $5.67)

                        2 pieces, 2" abs slip x 2" female pipe thread fitting @ $1.46 ea

                        2 pieces, abs 2"MPT cap @ $0.82

                        2 pieces, 1/2" NPT x 3/4" PEX

                        I went all out on expenses for this one and paid $2.50 each for these solid brass babies. The PEX style fitting works better than a traditionally used barb as it is easier to remove the hose from the fitting when the unit needs recharging. However, if you are on a tight budget, they are available in plastic which would be 1/2" npt male x 1/2" male barb. Yes, even though vent lines are 5/8" the 1/2" barb works very well and is easier to reomve. These cost $0.54 each

                        2 pieces gear clamps @ $0.30 each

                        you will also need some foam cut to size to prevent the carbon from falling into the vent line.

                        In the picture below you can see all the parts I listed above UNQUOTE

                        Attached files

                        Alan Teed
                        1996 Wendon Sky Lounge 72'
                        Gig Harbor, WA
                        1994 Bayliner 4788
                        2006 Hylas 49' SY
                        Bayliner 2855
                        1977 Cal 34' SY
                        1981 Hunter 33' SY


                          Further to my earlier email with the reference to and instructions for building a vent filter, this will only solve part of the problem. It will significantly reduce the dispersal of the odor from the tank vent but the odor is still in the tank and you will still get a whiff or more from time to time. We eventually and totally solved this problem and now have a completely non odorous holding tank/toilet system by replacing both heads with fresh water units and replacing all the sanitary hoses. We did not even have to clean out the holding tank, just treated the residue in there several times and flushed with fresh water when replacing the above mentioned items.

                          The smell which is so obnoxious is not in fact human waste, which breaks down quickly, it is the dead and rotting sea organisms that are brought into the tank with every salt-water flush. If you flush with fresh water exclusively you will not get this smell.
                          Alan Teed
                          1996 Wendon Sky Lounge 72'
                          Gig Harbor, WA
                          1994 Bayliner 4788
                          2006 Hylas 49' SY
                          Bayliner 2855
                          1977 Cal 34' SY
                          1981 Hunter 33' SY


                            One scoop of OxiClean, powder form.

                            Costco sells it for $19 a box (about 11 lbs).

                            I'm over 2 years with no smell and still on the first box.

                            One scoop when we head out on a weekend trip, one scoop after we're back and do a pumpout.

                            Try it. What's to lose? If it doesn't work (it will) you can always use it for household purposes.
                            1999 4788


                              I had a similar problem on my 3870. I ended up replacing all of the hoses from the heads to the tank. Wasn't fun, but it fixed it.