I have a 20 gallon reef in a 5x4m room. During summer our temps are around 35 degrees Celsius (91 Fahrenheit) however can get up closer to 40 at the hottest days of the year. Atm I’m using a 2.5kw split system in the room set at 25 degrees and a cooling fan on the tank. Is this the most efficient way or would a chiller be more efficient? Also considering the fact I’d have to spend 600 dollars to buy the chiller when I already have an aircon.