Water Quality

• If the water is turning green too quickly, take a look at your cleaning regimen. How much water are you changing, and how often? You should be changing approximately 25 percent of the tank water every week, with a full cleaning at least once a month. Clean the filter frequently, but be careful not to destroy the beneficial bacteria that helps deal with your turtle's waste.
  
  

Chemical Treatment

• Algae blooms can be fought with chemical warfare. A number of algae fighters are available for purchase at your local aquarium store. When purchasing one, check to make sure that it is safe for your turtle. Treating the tank with an algae fighter is very easy. Just follow the directions that come with the product, add the appropriate amount for your tank and watch the water clear.
  
  

Light Exposure

• One main cause of tank algae is too much light, so take a look at where your tank is located. If it is near a window, consider moving the tank, covering the window or covering the side of the tank facing the light source. If tank placement isn't an issue, consider reducing the amount of time you leave the aquarium light on. Tank lights should be on for 10 to 12 hours to mimic the day-night cycle. Reduce the length of time the light stays on by two hours, and see if that helps. To get a head start, try covering the tank and blocking all light for a few days.
  
  

Algae Eaters

• Another way to control you algae problem is to add algae-eating fish to your turtle tank. Of course, you have to be careful because your turtles will try to eat the fish. Choose a fish that is fast-moving and, if possible, larger than your turtle. Consider choosing a large pleco; its spines may provide some protection from the turtles. Whatever you choose, be sure to add hiding areas where your algae eater can get away from the turtles.