My RS salt alk is 11. I keep the tank at 10.5 and it has been that for 18 months. If I go lower my pH drops to 7.8/7.9. With the alk at 10.5 the pH is 8.0/8.1. With a pH prob I know what the alk is because the correlation is spot on when I test alk. Pretty easy way to monitor what's happening. I don't have tremendous growth rate but the corals look great.