Plants will only photosynthesize for a certain amount of time each day. I'm
not sure they could handle two different periods within a day since they
are, of course, not used to that in nature. They would probably start in
the morning with lights-on, then try to continue even after the lights are
off. After about 12 hours they would probably quit trying, then when you
turned the lights back on it would be too late. I am not a botanist, but I
believe this to be true. I would not recommend splitting the time. I
personally leave mine on from about noon to midnight since I basically only
have time to see my tanks at night. Of course on weekends I hate to see
dark tanks in the morning, but.....

Jody

"Bill Beam" wrote in message
...
I'm trying to get rid of some green hair algae and found out from
reading these boards that I'm leaving the light on too long. I have
been turning it on when I get up - about 8:00 AM and off at about
11:30 PM. Plants seem to be doing great but the algae grows on the
plants where the light is strongest. Anyway, I would like to have the
lights on to see the fish when I'm most likely to be near the tank.
These hours are in the morning and before I go to bed. Question then:
Can I turn the light on from 8 to Noon - then turn it off and then
back on again at 9pm - 11:30pm? Will the plants grow OK and I'm
guessing less total light will cure my algae problem? Guess what
I'm asking is - Do plant's need continuous light or is sporadic light
for the same amount of time OK?