I've recently seen a drop in quality of my home brewed beers and I'm trying to eliminate causes of possible infection. I've recently also switched from using bleach extensively as a sanitiser to Starsan (cleaning first with oxy cleaner like I know a fair few of you do).
I've noticed that most of my fermentors have a thin film of white coating (this can be scratched off easily) even after scrubbing, oxy cleaner and bleach or starsan etc.

Question is - would you chuck these and replace them or can you advise of possible deep clean procedure?
Any advice welcome.
Cheers