Allan, that is the same unit I have and I run it 24/7. It does not lower nutrients, It raises ORP a bit and lowers pathogens. I know some people run their U.V. on a 12 hour cycle to save on energy costs and lower tank heat.

It is my opinion that a U.V. sterilizer should never be run in series with the display supply line, I do not want the plankton supplied to the display killed.