UV, Or Not UV? That Is The Question.

I struggled with dark, bearded type algae on my aquarium plants for several months. I tried different methods of getting rid of it, but to no avail.
Despite the assertion that UV filtering reduces resistance of the fish to disease, I decided to give it a go.
I already had a Vecton 300 ready and waiting. All I needed to do was replace the bulb and switch it on.
In the space of ten days, I would say that more than 90% of the algae has disappeared and my plants are now looking very healthy.
I'm experimenting a little by trying a week with the UV on, followed by one week off. Does anyone know if that will reduce the effect on the resistance of the fish to disease? Or am I wasting my time?