Yep I did read lots of article about CO2. what I am curious about is that, by turning on light 12hrs, 3wpg, 25ppm CO2, aren't we basically providiing excess to the plant? (that's why my plant overgrown the tank very quickly). There should be a minimum required amount of both light/co2 for the plant to just survive and grow at an unoticable rate. This mean that one could save alot on CO2 tank refilling, Lamp life, electric bill, fertelizing the tank and water changes too (traces element are not being depleated as quickly anymore).