I recently had my water tested at a local Sears store and was told that the hardness reading was 13 GPG. This sample was taken from an outside outlet that does not pass thru the softener. I have had my softener set at 14 GPG, but I was advised by Sears that the setting should always be 5 GPG above the hard water reading. In my case, they advised me to increase the setting from 14 to 18, an increase of 5 above the hardness reading. Any suggestions?