Without the lower temps you're going to sacrifice a lot of dissolved oxygen,
but there are other ways to deal with the higher temps and preventing bad
growth in your reservoir.
Beneficials are a way of keeping slime/root rot at bay and are relatively
cheap to brew your own tea. There's a great thread on how to do so
found here:
https://www.rollitup.org/dwc-bubbleponics/361430-how-breed-your-own-beneficial.html
Or you can go the route of using a conditioner like Dutch Master Zone
this will basically kill off any and all growth in your reservoir, good or
bad. So don't use the two in conjunction (beneficials and conditioners)
as you will kill off your beneficials and was them. h2o2 is also similar to
this approach as it will kill off growth in your reservoir. Many people
refrain from using h2o2 though as it's a harsh chemical and can have a
negative impact on your roots as well.
The benefits from a lower temp will be your best solution as you can add
your beneficials as well, and your DO levels will be optimized by the temps
being low and your rootzone will thank you for that.
View attachment 1319050