That makes no sense at all. Is the sun is up for only 4 hours a day? An
aquarium is suppose to mimic the natural habitat of plants and animals.
Many aquarium plants come from tropical regions of the world where
their location on the globe means they get 12+ hours a day.

Yes it's true, there are several (many?) types of algae fish won't
touch.

A hard lesson I have learned: The presence of excessive algae in your
tank means there is a nutrient imbalance. It seems that whatever
nutrient is in excess, determines the type of algae growth. I had an
excess of phosphates in my tank and consequently grew LOTS of BGA (blue
green algae or cyanobacteria).

Read up on it. There is lots to learn!

My aquarium info & pics at:
http://www.geocities.com/spiral_72/Spirals_page.html