If you need a temperary solution before the UV filter gets going next year, try putting water plants in right now. That way, the plants will be able to eat most of the nutrients in the water so that algae problem will not be a major issue.

 

My parents have the same problem in their Koi pond. Its usually a problem in the summer. For the most part the UV lights does the job; but we are also considering setting up a gazebo or some sort of canopy to provide shade to the pond. Our neighbor's Koi pond doesn't have the same algae problem in the summer months as us simply because they have a gazebo providing shade to their pond. Also adding plants to the pond will also help.

In the mean time, we've been using Tetrapond Algae control to treat our pond. It takes the chemical about 2-3 weeks to clear our pond after every algae bloom. We've also been draining and cleaning our filter barrel to get rid of dead algae during our bimonthly water change. Treating the pond deoxygenate the water so your fish will become more lethargic, so it's a good idea to use an air pump to aerate the pond to help the fish.

Hope I can help...

 

That thread needs to get moved in here.

 

I had a little luck with catfish. Some types of catfish will eat the algae. It is sort of hit and miss. I had one catfish that ate all the algae in the pond within 2 weeks and I never saw a problem again until he got too big for the pond. I got another of the (supposedly) same species and he only ate enough to sustain himself. He did not grow very fast, and the algae did not get under control. It might be something worth trying.