You might want to try a slower flow, or smaller pump, the slower, the better on UV sterilizers. You will not "see" a huge difference, but if you take very good pictures before and 2 months later you will.
On UV sterilizers, I buy one recommended for twice or more the tank size, and use half the recommended pump rate, just to be safe. The longer the water is in contact with the light the more effective the light is. Use your own discretion. You could just dial down the pump you are using.