It produces copper ions which act as an algaecide. Unfortunately, copper can stain pool surfaces and turn blond hair green. Good news is, proper levels of chlorine (in your case produced in the generator) is all you need.
Is the sorta flat thing connecting from the sand box to the outtake valve the 'plates'?
That looks like them. There should be no build up on the plates. Make sure you look between them too, you may have to remove them from the container to do so. If you are seeing build-up, that is a chemistry issue.