That is not a definate. First set up the lights so they are not sitting directly on the tank. Make sure that you can get a good air flow under the lights, Then you can use a fan to blow the heat away from the tank. Then make sure that you do not use the glass covers over the tank. No matter which lighting you choose you do not, should not use the glass covers over the tank. It inhibits gas exchange. That being done, your tank will hardly ever get over 82 degrees. And that is a very good temp to keep your tank at. I know that most of the sites say 78. But my personnal opinion is they say that so most will think they need a chiller, and they will buy them. But the fact of the matter is, that if you go to Figi, Austriala and the Phillippines where these fish are mostly caught, the water temps were these fish are caught run at about 79 -83 degrees. So a tank that is kept at 81 or 82 degrees is not in danger. The danger is the temp swinging back and forth to much is the real danger.
As far as knowing the temps of these area, I know for a fact the temps of the Phillippines, I lived there for over 15 years. I spent a good part of each and everyday in the ocean. The water is definnately warm.