I have an Autopilot Digital Nano. It is saying the salt concentration is 2700 ppm (with no correction applied). I know I need to add salt, the question is how much. The salt strips I purchased from the same place I get my test chemicals (and advertised on this site), Aquarite I think is the brand, says 2250 ppm. So, which do I believe? How accurate are the salt sensors in the SWGs?