The Problem:
Green water is just an extreme algae problem.

The Cure:
Do a 100% water change, and even rinse out your gravel. go down to the pet shop and get yourself a phosphate sponge. They, amazingly, work. If you notice that it stops working, take it out and let it dry, I dont know why but it does rejuvinate it when you dry it out. Keep your light on under 12 hours a day, usually less. If you are using infrared along with your basking light, try turning it on only at night. I don't know why anybody would do this, but some people prefer to. Good luck y'all!