Both of those problems (cyano
bacteria is the other issue you have) are caused by excess nutrients. You're putting in more nutrients (food) than your taking out (skimming and water changes). The algae and bacteria are consuming what is left. Although there are methods to control the problem what you really need to do is find out the cause and eliminate it.
How often do you feed and how much water changes?
Reduce feelings to once every 2-3 days. Are you running anything to reduce nutrients? Any purigen, GFO
or anything else? Do you have a skimmer?
For control you can reduce lighting and increase flow on purple cyano
areas. But that won't get rid of your problem, it will just hide and/or delay you seeing it.