How do you make salt water for an aquarium?

Saltwater is generally made from commercially made salt (specifically for marine aquariums, not "aquarium salt" used for cichlid tanks) and filtered freshwater. Some people living near the ocean collect natural saltwater, but that can be polluted and usually needs to be filtered (which may cost more than making saltwater).

Go you petco or petsmart or anyother place that sells fish they should have instant ocean sea salt their the ratio it 1/2 cup of the salt per gallon read the box to make sure