Here's an interesting article (the final installment of a four-part series) regarding reef water temps. It recommends a range of 77 to 82 for reef tanks, but suggests that it might be useful if temps reach into the mid-80s occasionally to "promot[e] higher thermal tolerances in corals, reducing the risk of disaster in the case of high temperature stress."
I figure it is a transference thing. We humans like to keep the air cooler inside then the air outside. So we figure the fish would like a tank cooler then the ocean. :lmao:
It really depends on the inhabitants of your tank. But that is basically tropical ocean range. The more important thing is what is the full range? You say it is reaching 80 and 82, but not what it is reaching it from. 82 in itself isn't bad, but if your starting point is in the mid 70's then it could be.