I used to live in an apt and my tank was a 29gal with MH for lighting. In the summer it got REALLY hot in my apt, the sun beat on the side of the building where our windows and sliding glass door were. I put up styrofoam in the windows, added a small window shaker, and hung a blanket in the doorway from the area where my tank was and the hall way so the cool air stayed in the tank area and living area. This worked really really well. Living in Oregon, i don't think a chiller is necessary. We really only have to worry about maybe 45-60 days of the year where it gets over 80 degrees, and there are many ways to keep the tank cool otherwise.