I get full sun from morning to night and am inSouth Texas were it is hot!!!
I usually get pea soup before all the plants
fill back in. I'm running an 80W Aqua UV withmy 2500 gallon pond. UV's
definitely work on the pea soup.

I think you said the magic words....algea until the plants fill back in....I
think if you want an extra expense....and they can be expensive....and you like
gadgets and machines, and you don't mind killing every living thing that is in
the water that goes thru the uv ( including good stuff) then by all means get
a uv light.....If on the other hand you want a natural pond that will clear in
a few weeks, I would spend the hundreds of dollars the uv will cost, and get
a few beautiful lilies. Jerri

http://www.fringeweb.com/Ponds/JerrisPond