LOL.. hey did you know your pictures are upside down..
There is a a triangle of balance. Light, CO2 availability, and Nutrients.
If any one of those is out of whack then algae is the results.
We need more info. What type of light are you using,
I'm aving a hard time seeing what the brown spots are.. It might be to much light intensity. But more info would help in that regards
Can you adjust the height of your light.. This is a nice advantage to have