Product review (1 stars): This can't be good. I get no discoloration
I don't know why this filter begins to fall apart after a single night's use, but it does.  After two nights I find grit and pieces of the black cover floating in the humidifier base.  This can't be good.  I get no discoloration, just the black housing in bits and pieces.  I'm sure it works in wicking, but I think I might try a different filter or unit.  Yes, I rinse and use a microbial conditioner.  Don't know what the problem is.