What plecos are you keeping? Most of the most commonly kept species in the trade such as hypancistrus, l134 and similar actually prefer warmer temperatures.
I have L027( Armbrusteri), L200, and otocinclus Cacoma
The L027, and L200 would be ok a bit higher, don’t think the oto’s would though, the tropheus are ok at 28, but dissolved oxygen soon starts to become a problem
I cannot (not prepared to) turn the tank into a jacuzzi
I am out all day (at work), so required a 100% solution
I run a GHL computer which controls temperature, and when i ran t5’s, it dimmed the lights as temperature rose (which obviously helped), leds, have less impact on water temperature
Problem is once the sun comes round (after 1230 ish), even with windows open, the temperature in the “fish room” continues to rise with time, i have put sheets of 20mm polystyrene inside the windows, which helped a lot, but i still couldn’t keep water temp below 30 (when i got home), i used to but bags of ice cubes in the tanks, as the temperature dropped, the fish became more active
The chillers mean i can keep the tanks at whatever temperature i desire, I have lost zero fish since purchasing them, and would purchase them again in a heartbeat
It’s clearly best for the fish to have consistent parameters, the tropheus continue to spawn even in this weather, so i know they appreciate it😊