While retrieving the resin datasheet from my local water treatment vendor, he mentioned they liked to salt with 9 - 10 lbs, especially for high hardness water. I assumed he meant per cubic foot, and not total for my 1.5 cu ft system.
I have been getting pretty good results based on the slippery soap feel and Hach 5B tests, neither of which are that accurate near 0 GPG.
Any reason I should increase regenerant concentration because my feedwater hardness jumped from 7 GPG to 27 GPG? All I did was reprogram, and with the exception of shorter regeneration intervals it seems OK.
Edit: I am currently programmed for 30K capacity, BF time of 12 minutes through 0.25GPM BLFC for 9 lbs salt. Also, I have a tankless hot water heater so to some extent I am protecting it from scale. With this in mind "feels soft in the shower" may not be the most appropriate metric of adequate results.