I've always had problems keeping my system cool enough so I have froze gallon jugs and threw them in my reservoir to help keep the roots cool. Make sure you keep the light out, maybe wrap the buckets in some sort of material. I wrapped mine in some material almost exactly like what is used to make bubble bags for hash with canvas and a plasticy/rubber on the other side. Good aireation is key to temperature control. Make sure those suckers are bubbling but don't raise the water so high as to touch the bottom of your net pot because the bubbles will wash away your substrate. I leave about an inch or two, at least that's where I drilled my drain to regulate the water level. Black absorbs heat, white reflects, keep that in mind too. Happy growing!