Installed my SWG yesterday and added the salt. Salt came from Pinch a Penny in 40# bags. This morning the Polaris was cleaning and picked up quite a few hard white particles - looks like coquina. At first I thought they were PVC shavings that came from the pipes that were cut, they weren't. Then tried to tast one thinking it may have been salt that had not dissolved. Anyone know what this stuff is and is it normal to have these remnants when adding salt?