Wattage dosnt matter . We forget that the lighting we use is a spot light theres no shift in daylight in ower tanks. In the barrier reef the coral only get 5 hour of direct sunlight theres no spot light effect on them the hole day, As the hours go by the suns rays move away from them, So why not do the same as nature . All we are doing is stressing ower corals out from giving them to much light a day , thats why alot of reefers get slow growth and pale colors .