"RichToyBox" wrote in message
news:ZlFea.191593$S_4.103338@rwcrnsc53...
Mike,

The simple answer is, when it starts to turn green. The UV is really only
good for clearing algae, and it is not needed until they start to show up.

snip

Does this mean, you could run the UV filter on a cycle? On sometimes, off
others?

BV.