Originally Posted by Calmwaters
Thanks Byron that is good to know hopefully since I have changed my bulbs the algae will stay away.
I was addressing the specifics in this thread, and rather briefly perhaps. But to explain more fully: algae needs light. Nutrients will always be available if fish are present, so with light--and any light--algae will appear. In planted tanks algae should be present but minimally. This is achieved by having a balance between light and nutrients. Provided the nutrients are all available, and the light is sufficient in intensity, plants will photosynthesize full-out, and algae does not have an advantage, though it will be present minimally. Once the balance is broken--which can be one important nutrient no longer available, or the light no longer sufficient--algae takes advantage. In a natural planted tank, CO2 is usually the first factor to be used up; this is why it is critical to balance the light period with the nutrients.
Light should always be the limiting factor, because it is easiest to control and without it algae cannot become a nuisance. If the light is not of sufficient intensity to balance the nutrients, plants will slow and perhaps even stop photosynthesis, and algae takes the advantage. With older tubes, the light intensity is weaker, and at some point becomes too weak for the plants' needs. This is why tubes must be replaced regularly, and not allowed to just "burn out." I have had algae increases which I determined were related to the tube condition, since replacing the tubes stopped the increase.