I would suggest a four-fold attack to the problem.
First of all you might want to see how long you're leaving the tank light on for. If you're getting sunlight (which is like crack to Algae) you might want to cut the tank light at night. Give the tank about 8-10 hours of light.
Secondly you should consider putting blinds or curtains on the window. Even if you use blinds and curtains that reduce (not completely block) the light coming in, you're helping the problem. Covering the tank with a decorative film on the back of the tank and the side facing the window will also reduce the amount of light to the tank. As for UV films, I'm not sure if that'll help all of that much. It might, might not...never had the chance to experiment.
Thirdly if you have the room in your tank for the extra bio-load, get a bunch of Otto-Cats (Otocinclus Catfish) are chow hounds when it comes to algae control. I have a pair of big ones and they're all but gnawing holes in the glass. I had an algae bloom and now 2 weeks later I'm having to feed them supplemental algae wafers to keep them alive. I've actually had to increase the light the tanks gets just so there's algae on the rocks for them to nosh on.
Fourthly, consider live plants. If you have life plants that are consuming all the nutrients in the water, there is less for the algae. This one is a little hit-or-miss since I've had times where it's worked, and times where it did nothing. Depends on how bad the algae bloom is.
In any case, if you can do some if not all of these suggestions, you'll have it under control in short order.
First of all you might want to see how long you're leaving the tank light on for. If you're getting sunlight (which is like crack to Algae) you might want to cut the tank light at night. Give the tank about 8-10 hours of light.
Secondly you should consider putting blinds or curtains on the window. Even if you use blinds and curtains that reduce (not completely block) the light coming in, you're helping the problem. Covering the tank with a decorative film on the back of the tank and the side facing the window will also reduce the amount of light to the tank. As for UV films, I'm not sure if that'll help all of that much. It might, might not...never had the chance to experiment.
Thirdly if you have the room in your tank for the extra bio-load, get a bunch of Otto-Cats (Otocinclus Catfish) are chow hounds when it comes to algae control. I have a pair of big ones and they're all but gnawing holes in the glass. I had an algae bloom and now 2 weeks later I'm having to feed them supplemental algae wafers to keep them alive. I've actually had to increase the light the tanks gets just so there's algae on the rocks for them to nosh on.
Fourthly, consider live plants. If you have life plants that are consuming all the nutrients in the water, there is less for the algae. This one is a little hit-or-miss since I've had times where it's worked, and times where it did nothing. Depends on how bad the algae bloom is.
In any case, if you can do some if not all of these suggestions, you'll have it under control in short order.