I don't know if I've ever heard a definitive answer for this. Some people
claim the split lighting prevents algae. Others claim plants do best with a
continuous, 12-hour "day."

Split lighting would be convenient for me, because I like the light on in the
morning, when I feed the fish before work, and in the evening, when I get home.
And it does get hot in the middle of the day in summer. However, it does seem
rather unnatural. For the fish, as well as the plants. I know I wouldn't be
happy with my day divided that way. So I'm sticking with 1x12, at least until
there's more info on this.


Leigh

http://www.fortunecity.com/lavender/halloween/881/