Heya, green water is frustrating isn't it?
The best thing to do is trouble shoot the cause, just treating symptoms may only give temporary results.
A couple of things it could be:
-photo period is too long (your lights should generally be on 8-10 hours/day, if you dont have a timer you can buy one for pretty cheap. Timers are worth the $10.00)
-light intensity & spectrum
-expired/faulty test kits
-phosphates in your tap water
-expired bulbs (typically change yearly)
If you can't figure out the cause you can always try some low light fast growing plants to compete with the algae.