Getting rid of algae in turtle tank...

Hi all...

I have a quick question... my roommate has a painted turtle in a 40gal breeder tank with river rocks as "gravel"

Now, the turtle's basking lamp is on for about 10-12 hours a day, which I understand is correct since its similar to daytime and nighttime.

The problem is that the algae in the tank, particularly on the river rocks, has been going out of control and we aren't too fond of the green color on everything lol.

I was wondering if any of you had any suggestions as to how to prevent that from happening? we don't want to have to keep scrubbing it on a daily basis off of each individual rock... that is a pain.

can we use the chemical stuff in the water that is used in fishtanks, or will that harm the turtle?

Thanks!

Just add aquarium salt 1tbsp per 10 gallons not table salt because iodine can harm thier liver and painted turtles have been found living in brackish water.