Holding Tank: Vent Filter

[thinwater]

Peggy is right; if not installed properly they can clog. But contrary to the flavor of this thread, there are a whole lot of folks that are happy with them. I have tested larger vents, treatment chemicals, and vent filters, and they can all work. The best choice... depends.

In my case the vent was very near a critical hatch, and a vent filter provided a perfect solution.
a. I have a cat and it doesn't heel much.
b. I installed it in a high location and provided a trap.
c. I still use a nitrate-based chemical (Camco Ultra or Forespar Refresh, both excellent). These reduce the odors in the tank, reducing permiation and possible odors from flow-back (we spray the chemical in the bowl before leaving--work great).

The canisters last ~ 2-3 years and can be refilled in 5 minutes for ~ $5.
Sail Delmarva: Holding Tank Odors vs. Carbon Vent Filter

[doublewide]

It's a "no brainer." Everybody is right. Pump air into the top of the tank using a bait tank aerator. This prevents anaerobic bacterial growth. Add KO or other product to the tank. AND build yourself an activated charcoal filter for the vent line. You can get the parts to build your own filter. Any home store can provide PVC pipe and hose barbs. Make it so you can open and close it to change the charcoal periodically. Buy the charcoal at the pet store. (It is used for aquariums.) Do them all. Each contributes to odor elimination.

[Dave852]

It don't like the filters because as others have tried to suggest (and I will put it in very non scientific language) you are inhibiting airflow which makes the smell 10 times worse due to the completely different bacteria now growing in your tank because of the reduced airflow. So why try and cover a problem with a device which introduces a new set of problems to deal with. I have seen ruptured holding tanks due to clogged charcoal filters.
Since becoming a believer is proper airflow I have not had any holding tank smells. If possible a 1" or larger vent should be employed.


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[Captndave1]

I installed a home size fish tank aerator pump to force fresh air into the holding tank and I have never any odor in the boat in the years since installed.

[SteveInMD]

My old boat had bad stinky odors from the vent lines when flushing the heads. On my new boat the problem has been completely eliminated, 100 percent, thanks to fresh water flushing. I do not have vent filters and do not need them. I do have a valve so I can switch to saltwater flush if necessary.

[thinwater]

Originally Posted by Dave852

It don't like the filters because as others have tried to suggest (and I will put it in very non scientific language) you are inhibiting airflow which makes the smell 10 times worse due to the completely different bacteria now growing in your tank because of the reduced airflow. So why try and cover a problem with a device which introduces a new set of problems to deal with. I have seen ruptured holding tanks due to clogged charcoal filters.

The only problem with this logic, particularly if treatment chemicals are used... is that it isn't true. Unless you have tested this assertion side-by-side (I have), why post an opinion?

That said, a filter is not the best answer if the other methods are sufficient.

[yachttie]

I have recently installed a holding tank but I ran the vent line back through the transom. That way any odour will exit behind the boat, unless I am sailing downwind. I believe in the KISS principle.
Happy sailing.

[peghall]

Originally Posted by SteveInMD

My old boat had bad stinky odors from the vent lines when flushing the heads. On my new boat the problem has been completely eliminated, 100 percent, thanks to fresh water flushing. I do not have vent filters and do not need them. I do have a valve so I can switch to saltwater flush if necessary.

What you described wasn't odor out the tank vent, it was odor in the head caused by sea water left to sit and stagnate in the head intake....they're two entirely different issues. If you solved it by connecting a sea water toilet to your fresh water plumbing, with only a valve in the intake, you're risking contaminating your fresh water supply with sea water AND e-coli from the toilet. Only toilets that are designed to use onboard pressurized flush water should ever be connected to the fresh water plumbing. Toilets that are designed to use both and switch between sea and fresh have a separate remote intake pump for sea water that uses completely separate inlet plumbing.

[Jens Jakobsen]

A Vetus charcoal filter inserted in the ventline works fine for us. - No more bad odeur.

Brgds/ Jens