Lights on for how long ?

[Parker]

There aren't any hard an fast rules about how long you should light your tank per day. Your tank and your preffered viewing habits will dictate what works best for you. There are some that say that corals can only uptake so much light per day and anything beyound that is a waste, I've see people throw out numbers of 5 - 8 hours per day. I would assume that this would change depending on the strenght of your lighting. I've never put much stock in these conversations as everyone and every tank is different, it will let you know what happening.

I have have 3ea 14k 400w D/E metal halides and I run my lighting from 4pm to 10 pm.