Epsom Salt (Magnesium Sulfate)
Used to treat dropsy (fluid drainage) and to increase GH without raising KH In freshwater aquariums.
Detailed explanation
Epsom salt (MgSO4) has two uses in aquariums:
As a treatment for dropsy: 1-3 grams per litre in hospital aquarium. Magnesium acts as an osmotic laxative by draining fluids from swollen tissues.
As a GH supplement: Magnesium sulfate raises GH (total hardness) without affecting KH (carbonate hardness). Useful for regulating hardness in aquariums with osmosis water.
Do not confuse with table salt (NaCl) or sea salt. Epsom salt can be found in pharmacies.