I kept my ST in a brackish set-up with CaCo3 substrate and approximately 1 Tablespoon of marine salt per 2 gallons of tap water. It thrived. When I started the tank the information on keeping these fish wasn't so good. All dats were labeled as brackish water back then. I don't want to peeve any of the purist but it worked well. With the choral substrate you can throw away your pH test kit. It won't ever change.