well there will be some debate about this, but i will tell you that 1.018-1.021 are perfect for fish, also 1.022-1.025 are perfect for inverts and corals. now u must also remeber that the salinity will flux depending on the temp. also i perfer to drip acclimate most everything except corals. never lost a single fish invert or coral. knock on wood. also with also with ph u also must remeber that in extereme ph levels it will alter how your fish are affectted by amonia and nitrates. i have worked at a few sw fish shops in town and i can tell you that the ones i have seen temp and droped have more turn overs than others. now i will not name any names but thats from personal experince. well i hope this helps