its crazy that i see like 4 different charts in here...all saying 6.5 is optimal, but i PH to 6.8 to 7 and get 22-30 gram freshly cut and weighed colas on 18" tall plants...lol thats not counting the other probably 15 grams wet buds on the bottom...ya its wet, but i wont lose but 1/3rd of my weight while drying...like i said just keep PH'ing to 6.5, and spending money on cal/mag...and ill continue growing as i do producing alot of high quality MJ while having a PH of 6.8-7.