yeah, i want to get co2 but those release regulators are so expensive, and i would probably need two of them. i might just wait till my harvest and then upgrade for my next grow unless i get an extra $500 sometime soon. i havent switched over to hps yet because i am waiting for that burnt growth to grow out just to make shure their ok. once their out of shock i will start to flower them. isnt the desired CO2 ppm 1800? how much do you think i will yield?