5 galbucket temps stayed too high, around 77 degrees. 27 gal res temps 73 degrees. after trying 3-4 different airstones, I settled on some 4 inch round, flat stones. They don’t get blocked with residue, and the plastic part that is inside the stone is twice the diameter, putting out massive amount with 6 in each 27 gal res. each res has own 6 outlet air pump. I started in buckets, but roots quickly fill the bucket, little circulation with high temp gives me root troubles. Moved to big res, still trying to keep res temps lower. My latest thoughts are to freeze nutrient solution in old 3 liter soda bottles, cut open the bottle and plop a huge ice cube of nutes into it.