Yes too much light (and on for too long) is the number one cause of algae! With live plants a balance has to exist between lighting, nutrients, and CO2. With low level lights (1-1.5wpg) you can get away with not having to add CO2 or much nutrients because your plant grow is very slow, however, once you begin to add more light you need to increase the other 2 or you will end up with an imbalance. This imbalance is what causes various algae blooms.

T5 lights have more penetrating power than other types of bulbs, so their wpg is actually decieving.

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