What Is GH?
GH, or general hardness, measures the concentration of dissolved calcium and magnesium in water — the minerals that make water “hard” or “soft.” It’s a different measurement from KH: GH tracks calcium/magnesium specifically, while KH tracks carbonate/bicarbonate buffering capacity, and the two don’t always move together.
Why GH Matters
GH directly affects fish and shrimp physiology — many soft-water species (like most dwarf shrimp and many tetras) need low GH to grow, molt, and breed properly, while African cichlids and livebearers generally do better in harder water. Caridina shrimp in particular are notoriously sensitive to GH and KH and are often kept in remineralized RODI water specifically to hit a narrow target range that tap water usually can’t provide consistently.
Shop GH Testing & Remineralizing
See Planted Aquarium Test Kits for GH testing, and the Shrimp King range for shrimp-specific mineral and salt supplements.
