Catalina 30 TRBS #2889 "Northern Light"

Vent Filter for Holding Tank

The rest of the modifications.

If air circulation is really the answer for minimizing holding tank odor as Peggy Hall claims, then the single stanchion hole isn't an adequate vent.

Perhaps a really good solution (if I were building the C30 from scratch) would be to vent the holding tank at the top of the mast where I don't care how much it smells. I'd install some sort of venturi apparatus at the top of the mast where both rising hot air and venturi effect would always create negative pressure in the holding tank and keep fresh air constantly moving through it.

A quicker solution that seems to be successful is to install a water filter housing (Home Depot $18) and replacable charcoal cartridge ($7) in the vent line to the stanchion. This solution is much less costly then West Marine's throw-away unit ($60 per year?) and less painful than suggestion #1, above. The charcoal filters are available at hardware stores and make a huge difference in the odor issue. Don't forget to do a thorough cleaning of the waste hoses and inner compartment surfaces every few years. Replacement of old hoses when odor permeates through the walls is a periodic necessity. I believe Peggy Hall suggests a way to identify hoses that need to be replaced.

This filter housing is mounted behind the port seat back cushion. Because the hose on the right side dips downward on it's way up to the base of the stantion vent, it requires that hose to be vacuumed prior to winter to ensure there is no trapped liquid that could freeze.

The filter is mounted in a space that is difficult to work in. If the housing is stuck shut after being closed for a year it's difficult to loosen it by hand in the confined space. Make sure you keep the housing wrench that comes with the filter.