Hydrated calcium sulfate. Used to increase hardness of water that is soft or neutral. 1 tsp. will increase calcium ions by 55 PPM and sulfate ions by 135 PPM.

GYP-T2           recipe size           $0.45           0.05 shipping weight

GYP-04          4 oz (approx. 20 tsp.)           $2.29           0.3 shipping weight

GYP-16          1 pound          $3.49           1.2 shipping weight