How long as it been since you've changed your light bulbs?
This might be of interest:
http://www.marineland.com/articles/31Lighting.asp
" General Lighting Guidelines
A commonly asked question is: how long should the aquarium lights be on each day? Since most of the inhabitants and plants for aquariums come from the tropical regions of the world, it is best to mimic the day-length of this region. Length of daylight varies little seasonally in tropical areas. Generally, the light period is 12 hours with an intense period of 9 to 10 hours. Keeping lights on for over 10 to 12 hours per day is of no practical benefit and can cause algae blooms. It is best to buy an inexpensive timer and automate the light system.
Another common question is how long will the lamps last? Usually lamps should be changed before they actually stop emitting light. The reason is that the color spectrum of a lamp changes as the lamp ages. While the lamp may still light, it does not emit light of the original wavelength. A common problem is for the hobbyist to use a lamp until it no longer radiates light. Lamps should be changed at least once a year, but preferably every 6 to 8 months. If, for seemingly no reason, your aquarium starts to grow algae, think about when was your last lamp change? If it was over 6 to 8 months, consider that the lamp's spectrum may have shifted and the lamp needs changing.
The deeper an aquarium or the more particulate material in the water, the more light that is absorbed and/or scattered, so less reaches the gravel or tank bottom. This is an especially important consideration in plant and reef tanks. Consider adding an extra lamp for each 15" of tank height over 20".
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Hybrid Mode
