Thanks very much aaronnorth, I will check that out.I see you are from Nottinghamshire, me too, Long Eaton.CheersYou say Co2 diffusion can harm fish
only at high amounts, (above 35ppm) but some people have run it at 40ppm. ou can measure the levels by testing kh & Ph and then reffering to the table in my sig, or for a permanent test gt a drop checker.