First off, you don't have to start every post with "massage to.."

Secondly, the International System of Units is based on the metric system.. so really it's all the same thing..no need for the ignorance comment.

And lastly.. you plan to have a 250watt hps with no ventilation and you want to add CO2?? I don't recommend this...and you should probably read into CO2 before you impliment it into such a small space...