Posted: Sat Aug 08, 2009 2:57 pm
Green algae is safe, and if it doesn't overrun the tank, it can make the enclosure look more natural. But once it starts, if you want to get rid of it (at least for a while), everything has to be cleaned really well, or it will quickly form again.
Real aquatic plants don't cause algae, but rather can discourage it.
Algae basically feeds on light, warmth and nutrients in the water (from leftover food, poop, etc.) Your tank is near a window (providing the light), the water temp isn't cool (and the basking lights add to the warmth along with the window light). You're also using an underpowered filter for the tank (an Aquaclear 50 would be better for a tank that size) which isn't keeping up with the waste your turtle is making. And if the water isn't being changed (at least partially) regularly, there's the nutrients for the algae to feed on.
Initially, you can slow the algae by moving the tank away from the window so the tank doesn't get as much light. A more powerful filter would help, as would more regular changes cleanings (you didn't say how often you did this, but algae can form quickly, especially in a 10-gallon tank).
I don't know how long you've had your turtle or how much he's grown in the time you've had him, but if you cut down on the lighting and the algae continually gets out of control, it may be that he's outgrown the tank and an upgrade is needed.
"You become responsible, forever, for what you have tamed." -Antoine de Saint Exupery-