the regulator will be psi with your bubble meter showing the flow rate.You then have to read the air co2 ppm and keep the area between 1200-1500 ppm od co2 in the air so you have to have a air meter or ppm controller or the cheaper co2 syringes keeping air temps between 80-85 f still doing full room air exchanges every 2 hours roughly.The regulator and flow meters are 1 part of the co2 usage setup