I found a way to manage the room heat AND the res temps with the same A/C unit. I use a standalone unit that vents out of the room to manage the heat of the lighting in my grow space. But I've had issues with res temps being several degrees higher than room temperatures. Solution: I fashioned a new duct out of cardboard and am redirecting the A/c flow to the side of the reservoir, sucking the heat out of the reservoir first before cooling the room with the air coming off that. It has brought my res temps to around 72. Still not "ideal" but manageable (as opposed to 80 to 82 degrees). I've got a reservoir full of white roots thicker than I've had in any previous grow and its only been going 6 weeks. I'm thinking about insulating all the other sides of the reservoir and just leave the heat sink portion bare.