Yes I did mis speak as I should have stated “ that it’s in my opinion to keep temp around 78 “ that being said some fish, and inverts can’t handle much more than 78 degrees . Corals although even if slowly brought up to a temp of 80 to 85 and keep them steady at that temp can handle it especially if the strains are from closer to the equator , but others do not thrive as well as at a temp that they are not used to . we get coral from around the world and from different temps and depths . I keep mixed tanks that I’ve found 78 a good all around temp and feel that it’s a good temp for all to thrive , fish ,inverts , and most fish except cold water species . There are a few other reasons I don’t advocate the higher temp but I don’t feel like writing a paper on it at the moment . But to name a few other then what I’ve already stated is my other concerns are Oxygen depletion, immunological issues , and stress put on the glue of the seams of the aquarium which I have first hand negative experience. As years ago I lost a 150 gallon tank keeping a tank at 86 degrees for a discus tank which blew out after less than a year . Discussed it with the manufacturer at the time and gave him all info including pictures of stand with level , temp, etc. they took the tank back and told me that the consistent 86 degree temp compromised the integrity of the glue . I lost two tanks from two different manufacturers back then from glue failure due to the higher temp . That being said glues today I’m sure are stronger but if you don’t have to why push it . No matter what temperature you may or not believe or tanks inhabitants can or can handle you certainly don’t want to have drastic changes happen fast . So again I should have clarified that it was my opinion and why .