tanker ask you of what kind of water you using, type of lighting and how long the lights are on??
Dohno, it might been a good while sense i maintained my marine systems, what i remember of Diatom Algae, i only had to wave a hand across the area were Diatom Algae is, which was often when starting a new tank, all over the tank, even on the tank glass walls which always cleaned off quiet easily. I do know that any eel tanks i started, Diatom Algae was the only algae i ever seen and it came off from the LR quiet easily without brushing it off, and the algae is often brown and can be dusted off quiet easily.
I also believe that there are no two tanks a like, that each person in how they set up their system and how the LR if positioned as well as the pumps used for the tanks water currents, if not placed in the proper position, one could see a different effect then what others gotten from their tanks. Like for myself, only once i seen in my tanks during all the years i maintained them, i seen a little patch of red slime only once, and i not used any solution like i hear others talking about, i only cleaned that area for my first step and watch it to see it appear again, it did. Then i looked to adjust the currents of that area, and it no longer reappeared.
I had never used any dosing methods for algae's, nitrates and nitrites, i maintained it the old fashion way, water changes.