I have a green spotted puffer and am running out of marine salt. At my lfs they told me that I could also use reef salt for my tank. I usually cut it in half, about 1/4 cup per gallon. Is it better to you marine or reef salt for a brackish tank?
Reef salt is usually more expensive and is not really necessary for a brackish setup (or even a non-reef saltwater setup). It is balanced more for the needs of a coral-keeping tank. The puffer probably won't notice a difference.