Where are you pulling the source water from - the refugium chamber? I assume you're emptying into the skimmer chamber? You may want to look at upgrading to a Sicce SDC 3.0. The electricity savings along will pay for the difference in short order. As long as the flow rate is at or below 233 Gph you'll achieve the required 90,000 µw/cm2 radiation exposure for parasites. Your total system volume is 112 gallons, so it will be a little undersized (but still better than no UV at all). You'll be getting a total turnover of about 2x every hour (I get about 3x with my 57-watt, but this is also running at about 60% of rated capacity - so I can dial it up to 5x if need be).