Biggest thing is to remove your res from the growroom this will drop temp and eliminate light leeks
if removing it from the room isnt a option then you will need to get a chiller.
If your pump is in the reservoir it will add heat. If you don't need the pump to run all of the time you might try a 1 minute on 4 minutes off timer, or an in line pump. Next big step is a chiller.... That's about all I've got..
I didnt mention frozen water bottles cause thats a major pain in the ass lol
having a pump in your res is not somthing you can go without! And not
really the issue if its only on during flood times.