Bro, not here to start a debate..just sharing my experience, how I wish the temp of the sea about 20-30ft is 25-27°c at the dive sites like tioman, Phuket, Philippines, etc..sad to say global warming..I just went to Koh Lipe n I m surprised by the temp of water there but the marine life was ok..an Australia instructor there told me that he love diving at water temp 28-29°c..
Ok back to reefing, my benchmark temp for fish only is below 30°c..my tank uses a fan (off @ nite, sometime off in the day too as too cold)..evaporation is being taken care by a gravity drip system using a float, so water SG will b constant I believe in strong flow in tank so that fishes will not swim so easily in a confine space like our tank..I learn that wc is very important for fish only tank coz in the sea, water keep changing & moving ard, so wc stimulate that in our tank..wc oso flushes n dilute any parasites (most fishes will have parasite or virus in their body like human, they can live is because their body immune system can contain it..when fish scratch against object mean there's parasite)..Colour vibrant or not depend on a lot of factors..highlight again, I m not an expert & still learning everyday.. cheers