Which product/manufacturer would you suggest? Reef flux?Fully agree with @andrewey.
Based on your pictures though and your losing battle I would recommend jumping to the fluconazole. It's a 14-day treatment with a water change at the end of it (If you haven't gotten all of it by the end start another treatment). I was having a major issue with GHA in our nano tank, 14 days later a majority of the GHA I couldn't get rid of for months is finally on its last legs literally one last rock in the tank that has it.
I tried a small contingent of CuC early on they just weren't enough
Tried vibriant over a 9 week period still had it.
Cleaning and scrubbing where you can during water changes.
I would say that the CuC and vibrant are more preventative than addressing a large outbreak issue. I've now added a more substantial CuC and will probably dose vibrant weekly post the fluconazole treatment.
Let me know if you have questions happy to help