Agree. It is easy to keep any algae under control, once you know what is causing it. Light is always a culprit for any of the green algae types, but some other factors may play into it too.
We need some data though. What is the tank size (length and gallons)? What is your light (be specific) and how long is it on daily? Are you using any plant fertilizers, and if so, which and how often? How often is your water change, and what volume? What are the plant species (generally)? What is the nitrate and pH reading?
I was browsing through 2003 issues of TFH yesterday in the Library, and came across an article by one aquarist recommending tearing down the tank and bleaching everything to get rid of the algae--even putting the fish in a bare tank for days to get all the algae out of their system. That is too extreme. Algae is natural, it is the source and basis for almost all life as we know it, and to eradicate it from an aquarium is a useless aim.
But we can and should keep it in check.