However, algae can become a real pest, and usually there are two culprits for it's cause: light and co2. No matter what anecdotes may be out there, most algae blooms(of any kind) are caused not by an exess of nutrients, but because of too much light and/or co2. The easiest way to control algae in a planted tank is to max out your co2(to that point just before your fish begin to suffocate) and then simply use the light like a gas pedal. If your co2 is maxed, and you have a steady supply of nutrients, all you need to do is worry about light. There's no easy answer about light. Light can be manipulated by adding/removing bulbs, raising/lowering the fixture, and increasing/decreasing the photoperiod. You'll simply have to experiment with this to find out what works best for you.