Hi Faiz ..Its Better to keep you chiller running 24HRS A Day..a reef tank needs stable temp bro..,,,as for you lights..depends what are you keeping lps or sps..but I Think a 12Hours Day And 3 Hour Moonlight would be good....Try Getting LEDS They will help you..in the long run..due to less power consumption...Or T5 'S Also work as well..but more heat and more consumption..Hope This Helped..~~Happy reefing..New to reefing want any advise? Whatsapp Me Bro if you wanna ask anything..