Even though the bubbler works effectively and is pretty low wattage, I ended up taking mine out when we started anchoring for longer periods.
Large diameter vents on opposite sides of the boat increase air flow significantly through the holding tank. I have'nt encountered many boats whose holding tank could not be retrofitted with additional vent fitting.
Often just replacing the existing vent line with a shorter, straighter larger diameter vent line can make it unnecessary to add a second vent...
[/QUOTE]Coincidentally, Peggy Hall, we started retrofitting holding tanks with additional larger vents after you suggested that on the Mainship Forum in the mid 90's. You should have patented it. You were a big contributor on that forum back then.[/QUOTE]
Thanks for the compliment! But I don't think it's possible to patent "use a larger hose."
[/QUOTE]On our current boat the design is better but the hose had developed a dip, allowing moisture to settle and effectively become a trap, blocking any air from flowing past. I was fortunate that the location of the dip was accessible and easy to fix using some cushioned hose straps. I also thoroughly flushed the line with fresh water and let it dry for several days. Once I raised and secured the hose to prevent the dip the tank smells all but disappeared. [/QUOTE]
Wouldn't it have been simpler just to shorten the vent line enough to eliminate the sag?
[/QUOTE]Lots of comments on venting the waste holding tank. Very important to install a vent to both port and starboard side. This allows cross ventilation and maintains good levels of oxygen in the tank. [/QUOTE]
You're correct that the key to odor elimination is prevention and oxygen is essential to prevention. However, It's not always necessary to cross ventilate...a single large diameter vent can often work just as well--sometimes even better. It can even be as simple as replacing the "vent" thru-hull with an open bulkhead thru-hull. There are some installations--tank buried deep in the bilge and/or installed on the centerline with too much "stuff" on either side to allow a short straight relatively horizontal run--that won't allow cross ventilation to work..when aeration is the only
good solution. Iow, there is no single "carved in stone" solution to holding tank odor on every boat.
And I thank all of you for all the kind words here about my efforts to help you find the right solutions for your boats.
--Peggie