our house is in a small valley, and it gets very windy. Under certain conditions, the yard smells like sewage. Homeowners in the vicinity have had similar issues, and solved them by installing a charcoal filter on the septic vents exiting through the roof.

These filters seem to be hard to come by, at least locally. Plumber friends have suggested installing a studor valve instead, and studor valves are much easier to get. Will they be just as effective?

I've also read that I can't just install a studor valve on every vent in the roof: at least one of the vents must be open to let outgassing occur. Is this true?

There are 3 vents: one 2" PVC, one 2" ABS, one 3.5" ABS.

Reading this, does anyone have comments or recommendations?