Strain and light. Ever hear of the gram/watt calc? Well people use it to kind of gauge their skill. A good grower is producing .5 gram per watt per harvest in their own comfortable style. To produce 1 gram per watt per harvest requires a SOG grow and CO2. 1 gram per watt per month (that's a real calc), I've concluded is a pure myth. No one anywhere has a guide to reproducing it. And I've searched.