Brown Algae Growth ? Next Steps ?

OK.. still learning the ropes here so I could use from guidance or confirmation.

I'm running a RAIN2 algae scrubber.
I installed in early April and to date all my scrubber cleanings has been a thick green algae.
Today, the algae growth was a brown color

I have all 4 lights connected and have had all 4 connected for some time ( maybe > 1 month ? )
Last week's algae growth was green algae.
I clean my algae scrubber every 7 days
Lights are on 18 hours per day

The one change I have made over the past week:
My phosphates have always read 0. This made sense since I was using GFO on my reactor and controlling my phosphates. I have been slowly reducing the amount of my GFO to get to a point where my phosphates would register. My phosphates are now .05
My nitrates have been stable at 25ppm.

Would this be the cause of the brown algae growth?
I did read online that brown algae growth was a sign of too much nutrients in the water.

I cleaned the algae screen today and removed the algae.

Should I do anything different at this point ( increase/decrease lighting schedule? unplug any of the lights? ) or just stay the course ?

Attachment 8044 Attachment 8046

This is typical when nutrients come down; it still filters and absorbs a lot. This is not brown slime from high nutrients; this is just brown growth from lower nutrients.

You can feed more if you want. Double the feeding for a week and watch the growth thicken up again.