my chiller does not have a temp setting:
There is no "best" temp for sps and lps. It all depends what you are after.....
Some time ago, somewhere, I did post some links and quotes from scientific articles showing how sps corals grew faster in higher temp waters. If you are after superfast growth, push the temp up to 29 to 30 degrees. Under NO circumstances should this be done by inexperienced aquarists though. This is literally hanging over the side of a bleaching cliff, and whether its worth the risk is debatable....
26 Is a safe medium either way, although I prefer to run my system a bit higher, and compensate with small water changes on a regular basis with cooler water.
Personally i believe chillers and their feed pumps should be configured to only run at certain times, something like a tidal cycle, bringing cooler water into the reef. Just like in nature. Tricky to set up, costly to say the least.... Ties in with my tidal exposure theories....
So when the lotto starting again??