I am so sick of trying to get actual numbers for co2!!! I have seen like 5 different estimates based on an 8'x12'x7'h area on how long a tank, 20lbs, would last. The calculators go anywhere from 154 hours to 3 days at 12 hours days with enrichment to 1500ppm...What is the deal man???? I just want to figure out how long tanks will really last and all the bs aside like no way to tell bs is driving me crazy.. How many plants, how sealed it is all bs.. Just how fricking long will a tank last with around 30 plants in a sealed area like this>>>?????! Propane? Tank(s)? twin regs? water chiller for propane water cooled? New dehumidifier if using propane to keep humidity down? I just want to increase the co2 from 300 to 1500 in the grow around 3 to 5 times per lights on cycle.. Don't want to keep it all the time there but I know that would be best???! how much best or better I don't know either.. I just figure if you, as one calculator said, enrich to 1500 3-5 times in 12 hours a tank will last but others have said they won't last but a very short time! What is the real deal?????????!! Does anyone know?????? I know that if you use co2 with small plants they will not have to grow to monsters to make a huge cola of bud so it is the best way to go but it is so hard to know what system will work? I mean this aint cheap to start and I don't want to fuck this up... If anyone, ANYONE, can tell me the skinny once and for all please, PLEASE, help..... I will wash your fucking car and kiss your monkey if you can give me a straight, right answer..... Thanks.... Will be forever in your dept...