Holding tank filter

[SILENTKNIGHT]

I have a 2006 Mainship 34T, When i flush it smells. But i traced the vent line from the tank to the starboard side vent port and there is no filter?

 

[Kaniksu]

Filters seem to impede the tank from breathing. Do you have raw water or fresh water flush?

 

[Bacchus]

I have a 2006 Mainship 34T, When i flush it smells. But i traced the vent line from the tank to the starboard side vent port and there is no filter?

You don't need or want a filter. You need ADEQUATE AIR / VENTING to allow aerobic bacteria to flourish. Get and readca copy of Peggie's (HeadMistress) book and take a look at my Bacchus website for my holding tank aeration project. I have since figured a way to run a new vent under the bed to the bow and have abandoned the OEM vent hose & ftg.
Best vent line are large dia,nstraight & short runs. If unable to do that a bubbler is VERY effective, lo cost and lo power draw. It should be run 24/7 anytime the holding tank is being used ( holds any waste / liquid)
Lots of threads here on this very topic but my solution is right from my 2008 MS 34HT

 

[SILENTKNIGHT]

i have fresh water flush, im thinking of just using a garden hose at the vent hose and back flush into the tank? Its too difficult to replace the vent line.
Maybey a little white vinegar & baking soda down the vent line?

 

[Bacchus]

Im in fresh water but the 34T vent is inadequate IMO even if clear. The small size, fuel vent type with screen and the distance & routing make it less than effective.
Cleaning it out won't hurt but I doubt it will make much difference.
I found NoFlex (or generic sodium percarbonate available on the web) as the best treatment I've tried.

 

[backinblue]

Your problem is not likely the vent hose itself, but not good ventilation of the tank as Don stated. A friend of mine has a very smelly salt water flush tank and put a filter on the vent and is happy, but filtering the vent is not normal and can worsen the problem. Better to first try a better way to aerate the tank and use things like No-Flex rather than a deodorant. This has been discussed extensively elsewhere.

 

[Comodave]

You need oxygen in the tank. Aerobic bacteria doesn’t smell, anaerobic bacteria stinks badly. You do not want a vent filter, they block air flow and can get clogged by overfilling the tank. Then the tank can collapse when pumping out. Either add an oxygenation system or add a second vent and get rid of the filter on the first vent. On our present boat I left the OEM vent and filter in place and added a 1.5” vent to each side of the boat so I get good airflow through the tank.

 

[HeadMistress]

As others have said, oxygen is the key to holding tank odor elimination, 'cuz when organic material breaks down aerobically (oxygenated) it converts to CO2, which is odorless...when it breaks down ANaerobically, it generates sulfur dioxide and hydrogen sulfide which are both stinky and toxic and whether you flush with fresh water or sea water makes no difference.

Replacing a vent line is relatively easy job and doing so usually results in a shorter straighter vent line, which makes it a lot easier for the tank to "breathe." If you can do nothing else to increase the air exchange via the vent, at least replace the "vent" thru-hull with an open bulkhead aka "mushroom" thru-hull. This not only increases the air flow in and out of the tank, it also allows you to put a hose nozzle up against it to backflush the vent line every time you wash the boat and/or pumpout. Anything that's tried to set up housekeeping in it will just get a water slide ride into the tank.

All of this and more is covered in detail in my book (see link in my signature below...just click on the title) and I'm always glad to answer questions.

--Peggie

 

[koliver]

I very recently replaced my HT system. I now have 1.5" hard pipe from the vent fittings on the new tank to an open, mushroom type 1.5" thru hull. The run is shorter than the original and using hard pipe, has no possibility of sags. The bigger thru hull has no screen, which, on the original, eventually clogged closed.

A friend had a Vacuflush installed. The installer put a filter on a 3/4" line. His filter gets clogged if he allows the tank to get full. It also stinks. I know.

 

[Marco Flamingo]

When we pump our tank, we have the freshwater rinse hose going and point it at our tank vent. Our single vent line is not very large and, at first, we could barely tell that it was sucking water in as we pumped out. After doing that several times, the vent made a much healthier sucking noise while pumping. My guess is that the tank had been overfilled many times over the years and layers of "effluvium" had crusted inside the hose. So what may be a 3/4" vent hose might have had an effective opening of <1/2". That, and now using a shot of sodium percarbonate* with every #2 flush has made all the difference. We keep the sodium percarbonate in this container for a "one shake per" application.

It hasn't completely eliminated all smell, but if we happen to get a whiff now it is more of a "low tide" smell. That is a vast improvement that I can live with.

* Good thing that it is Kosher.

 

[Airstream345]

FWIW - after reading Peggy's book we did three things to improve sludge (previous owner under maintained tank health) and odor:

1. Used lots of NoFlex digestor to break down sludge over time. This worked well but was expensive.

2. Increase the single vent line from 1/2" to 3/4" and used a straight thru hull as a vent.

3. Added an inexpensive 12V aquarium oxygen pump and created a "bubbler wand" to pump air into the tank/effluence.

We've virtually elimanted smells, we never have sludge and no longer need to use the NoFlex.

 

[Sea Q]

FWIW - after reading Peggy's book we did three things to improve sludge (previous owner under maintained tank health) and odor:

1. Used lots of NoFlex digestor to break down sludge over time. This worked well but was expensive.

2. Increase the single vent line from 1/2" to 3/4" and used a straight thru hull as a vent.

3. Added an inexpensive 12V aquarium oxygen pump and created a "bubbler wand" to pump air into the tank/effluence.

We've virtually elimanted smells, we never have sludge and no longer need to use the NoFlex.

Gee that cuts into my sales but I'm truly happy it helped
Mr Noflex