algae identification

I change my water (50%) about every 1.5-2 weeks, and the chemistry and clarity is excellent. Temp is 75, and PH is about 7.5. 125 Gal, Planted...and all except my fast growing Pennywort is growing this brown looking algae. I see it forming on the glass after about a week and you will notice...

I have noticed a build up of a thin layer of what I think might be algae on the sides of my fishtank? It looks dirty and clumpy and I really don't know what it is.

I am curious to to what type of algae this is, and what to do if anything about it. The pictures do not visualize it as well as seeing it in person. L I am referring to the dark green spots on the rocks. It is slimy, and Not easily removed off rocks. I have noticed that one rock is harboring...