Think we all suffering a bit with the heat , when we had the heatwave when pandemic kicked off around March April last year it was hot then ,
I used a few ice cubes direct into Tank .
Also you can buy ice cube packs that have about 16 ice cubes in , you fill them up from the top and seal then put into the freezer. You can make them up only fill half way , when done put a skewer through the top and float let the ice cubes melt in the pack in the Tank without the water entering you’re Tank .
Cheep and cheerful way to keep temp down in tank without effecting the water chemistry.