Algea stays yellow what ever I do. Its not a slime at all. In fact algea is very tough and hard to clean. It has fibrous structure, that you can see on first photo. I am using steak knife to clean.
Increased flow x2 last month. No effect except may be it grows even more now. I would not bother , but some algea is on the rocks. Very thin layer, but I thing its stopping coraline from spreading. I try adding iron, but see no effect . Should I try more of iron ? And if it increase filtering at all ?