I bought a 15 watt Aqua UV Advantage (Out of Pond) UV for around $100
shipped to my door. It worked overnight on my 1250 gallon full sun
pond early in the season. I liked it so much I bought a second that I
used for part of this season when the slight green water bugged me. I
really enjoy having clear water in full sun.... In addition, the UV
kill most parasites in the water when I run them in dual. That will
help me feel a bunch better during the winter.