well first I would post what you have in your tank that you feel may be affected by the heat. In all honesty I do not think that is too high of a temp. some keep there tanks that temp on a daily basis and have tanks that thrive. for instance if you look at reefvideos.com showcase #4
reefer Marte menesis' seahorse/ricordia tank thats what his temp is at all day and the sump is also plumbed to a mixed reef and sps frag tank and they are all that temp. Also keep in mind that natural reefs yes are dying/bleaching from the heat but reports say the temps of the water surpass 90degrees for days,weeks on end so a day or two at 85 is ok Imo
Decrease your photoperiod for the worst of it. BTW, under 85 for a limited time ( a few days) is not that terrible and it is the corals that care, the fish within reason don't really mind.
Last year around this time when I first got my halides, didnt even realize that my tank hit 91!!! It felt smelled like hot fish soup for a lil bit, thank god everything made it.
86 or higher, shut off main lights,aint no harm in less lighting for a few days.
note: water temp can only be as low as ur room temp.unless u have a chiller.
Last year, in this heat, my chiller would be on 24/7!!! Since I changed out all my big pressure pumps for more efficient ones, heat has not been an issue. My tank is at 80F right now and my room temp is 85 I'm about to turn the AC on though
If your temps break 86 I would shut everything down anything that adds extra heat that isn't absolutely necessary (ie skimmer pump, extra powerheads)