Thanks guys. Really help.
My reef is in the Main floor, 3 Mag9.5 submers'd for return. But problem is system is closed up - I mean I closed the tank with glass top to avoid dusting due to new developing still under going.
Last year (when I havent got the Reef setup yet) - My FW tank 90G was at a peak of 31 degree celcius at a time in summer. So I guess the reef would get abit hotter since the effect from the T5 and the 3 sump pumps.
Guess I'll need a chiller soon.
Now I need to do some research for this chiller problem - Since haven't enver try / knowing anything about it yet
Thaks guys for your infor.