Lime (Calcium Carbonate or CAC03) adds more supplemental calcium & buffers ph when added to bulk substrate, grain soak or casing mix. It also assists in loosening the substrate and stops your grain from clumping for that fluffy texture fungi enjoys. High-grade calcium carbonate. An essential addictive in every grow.
The general recipe is to add gypsum to bulk substrate, grains or casing at 1 parts gypsum to 15 parts bulk per volume, this will buffer sphagnum peat to a pH of 7.5. For a little extra minerals one can add kelp meal powder.