What size UV light for 1200gal pond

[Koi guy]

Hello my pond has been running for a year now and I can't get rid of the green algae in the water and I have heard that I can get clear water using a uv light but im not shure what size one I would need fo my pond?

 

[Meyer Jordan]

What size (capacity) is your pond?
How many and what type and size fish do you have?
Number of aquatic plants?
Pump and biofiltration size?

 

[Tula]

My pond is 1700 gallons and I use an 26 watt bulb.

 

[sissy]

18 watt and 5000 gallons

 

[CometKeith]

Hi Koi guy. Welcome to GPF. I usually buy my equipment from azponds. This is a link to their UV lights. If you click on the individual models it gives a lot of information about what size ponds they are suited for.
http://www.azponds.com/New_webpages/UV_selection.html