Thoughts on exposing filters to light source?

[GoFish]

Wondering if anyone has any input on exposing either filter floss or filter socks to light. My last tank had filter socks and was next to the refugium, if the socks were exposed to the refugium 6500k light they would accumulate a brown film algae (not sure of exact algae type). It was unsightly so I would put the cover that came with the sump blocking the light from hitting the socks.

On the new tank I made a custom filter holder directly behind the overflow. It uses filter floss and other mechanical filter media. Now my led lighting is exposing the top layer of filter floss to light. Also generating brownish algae

My 2 ways of thinking are either it's a good thing pulling additional organics out of the water acting kind of like an Algae Turf Scubber (ATS).... OR it's a bad thing, maybe a bad algae to have the tank water continuously cycling over?
I try to clean the floss every few days and replace every so often.

All ideas and thoughts welcome