check out Version 2 on this site I one of these. make sure if you make one of these to get the canisters with the buton on top this will alow you to degas the chambers with just a push of a botton
http://www.telic.us/SaltwaterFishTanks/DIYDenitrators/tabid/60/Default.aspx
http://www.telic.us/SaltwaterFishTanks/DIYDenitrators/tabid/60/Default.aspx
