Gill Passman wrote:
My understanding of UV usage in the marine aquatic side is that it is
used for prevention of parasites etc. Does the same theory apply to
Ponds as well with this UVC unit? Or is it just a water clarifier?

Just addressing this question to my understanding, mostly they are used as
a clarifier. They have to be of high wattage to kill parasites, and
considering the volume of water, not many people go there. Not to mention
we're talking outside where lots of parasites can enter the water at all
times. Thus it is more important to make sure water parameters are great
and fish have healthy immune systems.

I don't use UV.... if the plant to fish ratio is balanced it isn't needed.
Unfortunately most tend to hit a pond shop and go, "Oh pretty! I'll take
10!" And it isn't plants they're looking at. ;-) ~ jan