I am running the same ebb/flow and my 50 gallon rez is in the grow room also. Not sure what part of U.S. you are in but my grow room temp does not get too bad (75 to 78... 80 to 85 when hot outside) so rez water temp stays in 70 to 73 range and 75 when hot in the room. I have a couple of air stones so my water circulates pretty well. I use the frozen plastic liter bottle trick Tiny told me about. Like Keylime said, get a couple of air stones.

Your girls are looking good.