I've been using a hamilton bulb 14k 250 watt with hamilton ballast .. On a 100 gallon corner tank 1 light ... I just got a lumerek and 400 watt radion 20k bulb I wanted brighter with more blue ... I have all sps . My question is I was running lights on for 7 hours and I cut it back to 5 to start so I don't fry my corals . Is 5 hours enough its been 2 days and everyone seems ok ... Actually in seeing poloyp ext on corals that never showed this with the 250....watt it's just 5 hr doesn't seem like much ?