I don't use a filter with my pure oxygen system from Williams Brewing. Just hook the tube to the regulator and the rod, open the valve for 30 seconds, and I'm good to go. To clean it, I just put the stone in boiling water for a few minutes.
Tap 1: English Dark Mild Tap 2: American Brown Tap 3: American Amber Tap 4: Sour Belgian Brown Tap 5: Nitro Milk Stout
Kegged: Amber, Brown, Milk Stout
Lagering: Vienna Lager