I have CF
hoods over two tanks. I recently bought another hood to put over a third tank. The new CF
lights looked brighter than my other ones, which are about 8 months old. If your current CF
bulbs are a year old, I think you should replace them. My older bulbs do appear dimmer to me. If this is a planted tank, get ready to adjust your fertilizer schedule - the increase of light will probably increase the photosynthesis and may make the plants absorb nutrients faster.