Has anyone heard of Gypsum (hydrated calcium sulfate) for lowing the pH in soil? I'm growing in Virginia. My plants are Diesel Elvis #5 and Crack Weed. The soil is regular potting soil but I amended it with perlite, vermiculite and sphaghum moss. The nukes I use are Jacks Classic All Purpose 20-20-20, SuperNova 1-1-1, Black strap molasses, Peruvian seabird guano 10-10-2 and Alaska Fish Fertilizer (5-1-1), I recently stop using the fish fertilizer because my girls are getting slightly dugged up by animals. I think the fish fertilizer is attracting them to the plants. I am going to buy seaweed at the end of this week and start using that also. Some of my girls are 6 feet tall and others are 5 feet tall. Others are only 3 feet tall but they are in desperate need of transplanting which is slowing them down. I am in the midst of moving them again due to security issues, so it's really hairy now because they are so big. When things are settled and they are transplanted, I am going to take a pH reading. If the pH is too high, which I don't think so now, I wanted to know if anyone has heard of Gypsum (hydrated calcium sulfate) for lowering the pH level? I want to buy something now and keep it around in case I need it. I read about this in Jorge Cervantes' book Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible. Any help would be greatly appreciated. Thanks.