Temp over 84

Open the lid, if it has one, and have some fans blow over the surface, it will help.

I have 2 XP3's keeping my 100gal tank clear. They are located in the stand, behind doors which are weatherstripped (to minimize the noise). I leave those doors open during hot spells, because it gets quite hot there with the filters filtering, and the water running through them is effectively heated. Just an idea for those that have their canisters in a closed stand. I noticed about 2 degrees temp difference!

I also recommend using the average big household fan for immediate help. Around here ambient water temp is around 27C. With lights on, it may soar to over 31C and start to kill aquatic plants. Just opening the top and blow some air to the surface can bring down the temp back to the ambient temp.

Just my experience, hope it helps on a low cost to relieve the heat during short summer month (hey, it is summer all year around here).