It's all connected...

The issues you have with heat and pests all relate to poor airflow. I suspect you will find, as a I have, that a robust air circulation system that keeps your temps in the upper 70s, low 80s max, will also remedy the favorable conditions for fungus gnats, spider mites, various noxious spores... Are you monitoring humidity as well?

Yeah, experiment with some fans and air flow for sure. Now that you have pests, they are likely here to stay. Much harder to get rid of than prevent. You might address airflow, try your best, and then between your grows, make sure you clean your garden to the max with rubbing alcohol, bleach, etc., and let it go bone dry for a week or two. Start over with fresh air, and those little fuckers won't come around no more.