Yes that is what I presumed, but it has not raised. I am at a lost as to why it is not raising as expected. Does the SWCG have to be turned off for a few hours after I pour salt in?

To test my water I am run a dip stick test. Then I take the water sample to a pool store (tried two places for reliability). Each time the salt levels come out consistently low and within 100 ppm of my dip stick test. After the last bag was added, the "add salt" light went off for the first time on my sensor unit - however, that was short lived. After an hour the "add salt" light came back on. Pool store and dip stick confirmed 3900 PPM.

Great tip on the dual chlorine test. I will test at the return and at the skimmer to see if there is a difference.