I have 400 watts of T-5 lights in my 100 gallon. I just increased the times to 10 1/2 hours actinic and 9 1/2 daylights. Do you guys think that will be good. A majority of my corals, clams, and anenome are photosynthetic. I read that in natural coral reefs they have 12 hours of daylight. What do you guys think? Should I keep them that way, increase, or reduce the time?

i found that with 12 hours of lights i was getting diatom algea blooms, so i reduced them down to 8 hours weekdays and 10 hours weekends, plus actinics an hour each side of that, this gave me a great result. Just muck around, there is no right or wrong, what ever suits ur tank is best.