The larger the
nutrient tank, the cooler it will stay. Insulating your nutrient tank or putting it in a hole in the ground or doing both will also help. If you want to spend the money, there are nutrient chillers available.
I think that you would appreciate some lecca or hydroton mixed with your pearlite or better yet mix hydroton with coco-coir. For starting your plants check out
Sure to Grow Cubes they are the best that I have found.
Keep a close eye on your pH in the hot weather. It can take some pretty drastic swings as the temperature climbs.
God Bless and Happy Growing!
