This is commonly called shelf roughness. And your plater is correct. It happens when suspended particulate matter falls onto the horizontal surfaces of the parts and is "locked" in place by the continued plating action. This is usually an easy problem to correct.
First, the source of the roughness must be found and corrected. This could be a torn anode bag, debris and junk on the bottom of the tank, or a faulty filter. There are also other causes. Once the cause has been identified, it needs to be repaired.
Second, you need to remove whatever debris is already in the bath. 99% of the time, you can do this with the correct type of filtration. A 10 micron filter media is adequate in most cases. A problematic bath like this is should have at least 3 or 4 turnovers per hour, calculated with the media in place. I have seen numerous filtration systems that are grossly undersized. The manufacturer lists a flow rate with no restriction or head pressure. But when you add the media, plus any assorted piping and plumbing, you cut the flow rate down by a significant amount. I typically size my filters for at least 8 turnovers per hour (based on open flow rate) and I size my plumbing 50% larger than the fittings supplied on the pump.
-Dustin Gebhardt, CEF
Advanced Manufacturing/Finishing Engineer
Moen
Sanford, NC
