Hi bro,
Generally, pH levels ranging from 8.1 to 8.4 are acceptable for Saltwater tank. But, reef tanks tend to be a bit more sensitive and the optimum pH levels in these tanks need to be more towards the higher levels .
FYI, My tank's pH all the while is ranging from 8.5~8.6. All fishes are very healthy and corals growth are excellence especially the monti amd birdnest from frag to colony within 4~6 months time so I dun bother to bring it down !