Soyadude, you are wrong!

When a tank covered with lighting on top. The heat will generate on top of the aquarium faster than air-con to chill. You can ask gg... He is using those giant air-con which we normally used in office. But he has one inside his BEDROOM.

He was using 6-8 FL tubes. But the water temperature can't go down when photoperiod and he turned the air con on before the photoperiod. I told him to implement a fan or two to blow the cool air which from the air-con into the water surface. And then...yes. He got 22C most of the time.

So, unless you dont need to worry about the electricity bill. You can get an air-con + the fans. Or...implement the air-con just close to your tank and blow directly to the tank...