Where I live, the summers can get very hot and humid. Basic chemistry is that the hotter the liquid, or in our case, the
nutrient solution, the less gas it can hold. This will be my first summer trying this, so I am using a 2 line
pump from Eco, I believe, with two air stones. As it gets warmer, I will place frozen bottles of water in the reservoir in the morning, to help keep the temperature down somewhat. Also, as money avails itself, I will try to insulate the reservoir.
Also, the air pumps make the reservoir less attractive to mosquitoes. This is from my local mosquito control department, which the director lives next door.