Depends how often and how much water changes you do. If you do weekly WC and at least 12% . I don't see many fish. I do see cyano. PR are important but if your water par are good and things look good. No reason to run one.
thanks
I do 40 % about , water change but weekly . Currently I have a protein skimmer running inside my hang on refigium, however it makes noise and does not produce much junk. I run a carbon in the hang on. I have 3 fish