Gypsum

Gypsum is the common name for calcium sulfate (CaSO4) and consists of calcium carbonate and sulfur. It is a greyish powder used for making cement and drywall.

The main reason we use Gypsum is to add calcium carbonate and sulfur to substrate and casing material, which helps to stabilize PH levels to near neutral so it acts as a PH buffer as well as adding minerals which are beneficial for fruiting. It is also used in grain spawn preparation to prevent the grains from clumping.

It is NOT used to adjust pH levels as many believe.