Several reasons.

1.The pool is still curing after installation, and adding salt does not help IMHO.

2. Using well water can be a problem, especially with a SWCG. If there is any "bad egg smell", i.e. hydrogen sulfide, it will destroy the cell. Using well water means using a filter to remove iron amd other metals as well as hydrogen sulfide. Been there done that. Using unfiltered well water is the worst thing you can do to new pool being cured and to a SWCG.

Pat