Waste tank filter

If no one else answers...

You can do a little inspection yourself. First would be locating your vent opening on the hull, often near (or at least in the same general vicinity of) your pump-out fitting.

Next would be to look at hoses connected to your waste tank; the (usually) smaller diameter hose from the top, or near the top, of the tank and leading off somewhere toward the hull might be your vent line.

One you know where that vent line is, trace it from tank to hull... and if there's a filter, it'll be in there somewhere. Access might be from behind a locker, whatever...

-Chris

If you have vaccuflush toilets, absolutely...….but do as ranger said, it can't be too hard to trace the vent line (5/8" ID hose).

Yes I had a 420 mariner and it had a vent filter

I've found those filters to be more of a headache than it's worth. With the proper treatment of the waste tanks there is no need for those filters. If they ever get wet the carbon in them restricts air flow and you risk imploding your tanks. I removed my filters years ago and haven't had a problem since...

if you have vaccuflush toilets, you absolutely need them in most cases as the toilets pump so much air into the tank so quickly and it blows it out the vent and anyone standing in a 50' + radius gets a smell you cannot believe.

Absolutely not true if you use proper treatment in the tanks. I have two vaccuflush heads and you can be standing right next to the vent when it's flushed with no smell... Both are 1.5" vents with no filters, it's a straight hose from the tank to the thru hull fittings.

I use Noflex Digestor and you'd have to stick your nose in the vent to get a very little amount of smell.

The problem your describing stems from boats that just use perfume in the tanks.