Charlotte Pipe3 x 6 x 1 1/2 DWV Drum Trap W/CLEANOUT DWV (Drain, Waste and Vent) (1 Unit Piece)

I'm using this upside-down and filled with limestone to make an acid neutralizer for our furnace's condensate pump. Works beautifully, and much much less expensive than the "one time use only" filters that you can buy elsewhere. Just make the condensate enter at the bottom, and exit to the pump through the top. Just google for instructions :)

Provided odor seal as needed