You know, global reef temps vary quite a bit. I will say this, the water say around Fiji and Tonga where the Walt Smith stuff comes from is relatively cold. Mid to high 70s. On the other hand Red Sea say is often in the low 80s and I believe that the Bali stuff is high 70s to the 80 range. As a generality, however, bleaching events are associated with increasing water temp. I dunno 74....seems low, but staying out of the 80s seems like a reasonable thing to do...not that the reef can't take 82, but why push it?