"Christopher"

UV's have a couple of planted tank uses.
One is for green water
The other is for the 24 hour period after a water change.
So you will only need to use it once a week after the 50% water
change.
They do no good after this period.

I don't use them on my tanks personally. Don't need too.

Try a credit card for getting algae off the glass.
I think you'll find this is the best use for a credit card rather than
it's intended purpose.

If you address the CO2/nutrients, cleaning the glass is seldom an
issue.

Regards,
Tom Barr