I own the same product and I didnt put on my new tank! I didnt see it do anything for my tank! I had it on a 46 gallon bowfront and had iton the tank from day 1, and i still had fish get ich! That was the only reason i put it on was to help with the ich! Also I had a rio1100 pump on mine and found out that was to big of a pump!! The mag 5 you are running is pushing the water thru the light to fast to let the UV light kill anything! Here are the specs for the product! Good luck with whatever you decised!
Article Turbo-Twist 3x UV Sterilizer
UV Lamp 9 watt
Rated Voltage AC120V
Rated Cycle 60Hz
Rated Power 10.2 watt
Wavelength of UV Radiation 253.7mm
Life of UV Lamp Approx. 8000 hours
Aquarium Volume Treats up to 125 gallon saltwater or freshwater aquariums
Flow Rate 100-200 gallons per hour
Size of O-ring Inner 12/outer 16mm, inner 16/outer 22mm
Cord Length Approx. 9 ft.
Irradiation of UV Radiation 9,580 W