Managing algae

The plant tank has always had an algae problem. Initially it was overrun by cyanobacteria (blue-green algae), and then it had an infestation of a brownish-looking alga. Adding some corys helped, since they disturbed the bottom and broke up the near-continuous mat. When I finally added filtration things improved a lot. Recently, however, algal populations started to climb again, and I had a small bloom of cyanobacteria. While I was gone over the weekend, I decided to switch off the light and just give the tank a little natural light that comes through the window. The effect was remarkable - after just 2.5 days of low light, the algal had thinned significantly. The plants look fine, the algae does not.