I was wondering if I should add aquarium salt to my tank. I have one betta, a few zebra danios, and a few gaint black tetras. I also have 2 irridescent sharks, and a few ghost shrimp. The tank is 29 gallons. I am trading the irridescent sharks back to a pet store, and I want to get some easy to breed fish, so I was going to get a Molly. I know they are kind of brackish, but that wont work in my current tank. At the fish store, they are kept in pure freshwater. I have read that these fish can also benifit from aquarium salt. Would aquarium salt hurt any of my current fish. Also, If I added it, how would I measure the amount in the water. Would I just measure for saltiniy, like saltwater aquariast do?