I personally don't believe that lighting for 2-3 hours, then shut them off, then back on would do anything but stress the inhabitants out. Now, by going with lets say a 75 gallon tank with 2 individual T5HO double bulb fixtures, if you were to have a mixture of bulbs, lets say 1x5000k+1x6500k in one fixture, and 8000k+10000k bulbs in the other fixture, and going with a daytime lighting interval like, 5000k+67000k fixture turns on at 8am, then the 8000k+10000k fixture turns on at 12pm noon, then the 8000k+10000k fixture turns off at 3pm, leaving the 5000k+6500k fixture finally shutting off at 5pm.
Then this type of lighting regiment would have morning lighting, then a afternoon mid day lighting bust with both fixtures, then ending the day with the normal lighting, this would help the plants grow in nice, healthy, and beautiful.
The best way to avoid any algae within a tank, is to keep up with routine tank maintenance, and have a steady flow of Co2.
