The Use of Epsom Salts in an Freshwater Aquarium

Magnesium sulfate, more commonly known as Epsom salts, can be an important contribution to your freshwater aquarium. It will help with osmosis in freshwater fish, which is the process of pulling water through the gills. Epsom salts are easier to find and often less expensive than the alternative, marine salt mix or calcium chloride, that may only be available at large pet stores or a chemical supply store.

  1. Magnesium

    • Magnesium speeds up the process of osmosis while helping to flush the fish's system during osmosis. Levels of magnesium in freshwater aquariums can also affect calcium levels because the two keep each other in balance. When magnesium levels are low, calcium levels can be low, and vice versa.

    Sulfates

    • Sulfates are the second major component of Epsom salts. Sulfates help to increase nutrient absorption and help eliminate toxins in your freshwater fish.

    Use

    • Epsom salts are often used to increase water hardness in your freshwater aquarium. Add .03 ounces per 2.64 gallons of aquarium water to increase hardness by .002 ounces per liter CaCO3. Epsom salt will increase the permanent hardness and does not evaporate or decompose, so do not add more Epsom salt until after a complete water change. Epsom salts also are used to balance calcium levels in the freshwater aquarium as calcium supply can decease when magnesium is low.

    Safety

    • While it seems counter-intuitive to add any kind of salt to your freshwater aquarium, Epsom salts used sparingly add such a small amount of salt as to be negligible and are safe for freshwater fish. Keep total magnesium levels in your freshwater tank below 1,200 ppm for safety.