Hi Shango, Paul, Jesse, et al, I am wrong, wrong, wrong! My Physics teacher would kill me (except that I have probably outlived the old f_rt by now)! Jessie is correct that the amount of gas cold water can hold is greater than warm water. Also, from what I have read Paul is also correct in that at "normal" aquarium concentrations CO2 and O2 concentrations are independent of each other. Me Bad! Roy _______________________________________________ GSAS-Member mailing list GSAS-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/gsas-member