Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Add zero salt to a fresh water tank.
Salt can be used medicinally under certain conditions, but if the tank always has some salt, then the medicinal effect may not work. Dosing depends on the fish.
Salt can be used if there is nitrite in the water. Do a big enough water change to keep the NO2 under 1 ppm, and add 1 teaspoon of salt per 20 gallons.
Some livebearers do better with salt in the tank, but it is always best to first set the GH and other parameters correctly. Then the salt is optional.