Interesting. I also check my O2 and it reads 0 ppm every single time. I would be concerned if I saw CO in my O2. As far as I'm aware, standards are for 10 ppm or less in scuba air an 3 ppm or less in oxygen compatible air.Originally Posted by rjack
To the OP, I found 8-10 ppm in some tanks while on vacation. I spoke with the boat captain and he apparently told the fill station and they changed the filters that night because the next day the readings were 3-4 ppm. When I'm out of the country I will accept up to 10 ppm if I am diving recreationally, 3 ppm if I am doing deeper than recreational depths. For my home fill station anything different than a 0 is unacceptable.