Thoughts on exposing filters to light source?

[GoFish]

Here's what I'm talking about... Haven't put any food in the tank for 2 weeks, just did a 75% water change, and replaced all filter media. The next day, brown algae on filter floss (the photo is 2 days after WC, no food)

**May have just figured out the nutrient source. I transferred over Nitra Guard bio-cubes from the last tank and had the bag sitting beside my return pump, just took the bag of cubes out and its pretty smelly. Maybe I'll rinse them off in NSW and put half back in

[hillegom]

I don't quite understand how brown algae grow with a light source. Are you sure it is algae? Maybe bacteria or?
My understanding is light grows green algae, or red. Brown is the stuff you see growing in the pipes and hoses when there is a lack of light.
Regardless, if something is growing, it is using up nutrients in the water column.
A good thing if you regularly export that.