Here is Red Sea's recommendation:
Aquarium Type Supplement Salinity Alk Ca Mg
frequency
fish weekly 31 7.0 385 1220
soft corals weekly 33 8.2 430 1280
Lps corals Daily/weekly 33 12.1 440 1310
Sps corals, frags Daily 35 12.6 465 1390
clams, fast growth
Sps corals - mature / Daily 35 8.2 430 1310
low nutrient
systems