[Travis L. Stevens]

What Greenbean says is true. On the other hand, I agree with UnderCoverDork in our home aquarium scenarios. While 6ºF difference over the course of 24 hours isn't going to hurt anything, it also wouldn't hurt to keep it a little more stable in case of emergencies like UnderCoverDork has given. AquaJern, I wouldn't sweat it and take the weekend to do a lot of research. Go to the library, use Google Scholar, and look through some reef books. By the time you read through all that, you'll be confident that you'll either want to stablize the temperature as a preventive precaution, or leave it the way it is.