I am running 26 plants now, in a re-circulating drip system, that has a 1/8 HP chiller incorporated into the loop. I put the chiller in to be more safe than sorry (I was young), but never have needed to use it. I aerate the fuck out of my reservoir and that combined with the drip, I have a LOT of air in the water. This summer my res temp got into the high 70's, with no rot root issues, because I air the shit out of the water. Chillers are a waste of money in my opinion, unless you have no air in your water. Then they are needed. The downside to chillers are they run hot (add temp to the room) consume power (save save save) need additional plumbing (pumps, hoses, fittings) and for a good one, it will cost you around $300, easy.
So, to anyone contemplating buying one, think twice. An air pump and a stone will do exactly the same thing, which is to provide O2 to your roots.