Have had diatoms/ brown algae problems for months until I added a stronger filter. No more problems now.
Diatoms don't really stick to plants, glass or decor. They just "sit" wherever they form or fall. If filter is strong enough and water circulation is sufficient, diatoms are sucked in the filter and "cleaned off".
I believe if I turn off the filter that I added, Diatoms will reappear in my aquarium. They do not have the chance to do so now as the filter cleans them off faster than they can form.