We have a unit that automatically takes concentrated quat sanitizer and dilutes it with water to the appropriate PPM. This PPM is not set by us, but rather the company that provides us our chemicals. They refill the reservoirs on a weekly basis. I test the concentration of the sanitizer every week and it's usually 400 ppm or higher. This week it was roughly 300 ppm. I am wondering if this is something I should be concerned about or if this is okay and the sanitizer is still good to use. Is there a general spec for the typical concentration of quat sanitizer?