Great looking tank, always wanted to have discus. Maybe next year will actually try. Having the same problem with the same looking algae now so a free bump.
Thanks. They are awesome fish. You can feed them right out of your hand and even pet them like a cat if you want to and some of them like it and push back. Just make sure to do a lot of research before you jump into this part of the hobby because it can be sticker shock and frustrating if they start doing the back stroke over night... When I first started I had one jump out of the tank and then a year later one decided to "shoot" in the middle of the night and rupture his swim bladder. Other than that no real issues other than ich once when I bought a plant from a dirty LFS. Thankfuly they all lived and I didn't do that again.