It's tough for me to say exactly what it will do to the temperature because I have never had as much of a problem with that. My temperature swing is usually from 77 or 78 degrees to 80 or 81. I don't have any fish right now but my soft corals don't seem to care. I typically keep the house at about 77 degrees. I often keep the small lid over the filter off of the tank which may have something to do with it. The light itself does get quite warm compared to the stock light, but it has a gap on each side that helps get the warm air out immediately next to the light instead of sitting on top of the water. There is definitely better air flow with the new light. In the end, it doesn't increase the temperature any more than the stock light. Sorry I can't give you an exact answer . I would be tempted to buy one and see what happens , then return it if it doesn't work out. Another option would be to put in the blue LED bar that I put a link to above. When the light comes on today I can see if that one gets hot or not. An auto top off could help with the water issue, but I don't have one of those.Can you tell me if your having any issues maintaining a steady temperature? The stock light get so dang hot my tank temp jumps to 85 degrees and Down to 76 when it’s off. The evaporation is ridiculous. The cover is supposed to help reduce the evaporation but the light contradicts this. I have a Siberian Husky that constantly is blowing his coat so I have to have solid lids on all of my tanks. I’m tired of fighting the temperature though.
We used to have a husky. It's amazing that anything can grow hair so fast!