If you put water in a white cup and it's green it is indeed an algae bloom. WC
's won't help as the algae will just keep multiplying and you'll be back to square one in no time. Black outs work sometimes but if you do that you have to totally block all light from the tank for 3 days and no peeking. Peeking allows light in which will give the algae an opportunity to multiply. Also it's not totally uncommon for algae blooms to come back even after a black out. The best, quickest, and most efficient way to kill the algae is by using a UV
sterilizer. The bloom is usually killed off within about 24 hours. This UV
has gotten alot of good reviews from people on the forum... Green Killing Machine Internal UV Sterilizer with Power Head at PETCO
If you put water in a white cup and it's not green then your having a bacterial bloom. They also return after WC
's. Again a UV
sterilizer is the fastest way to kill the bacteria in the water allowing the water to be clear again.