MO fiberglass

Did you ever figure out why the pool is chalking? This sounds similar to issue I am having.

Pool is 1 year old. Darker blue fiberglass pool. The pool appears to have faded to a light blue color under the water. The color change seems consistent on walls and floors. Almost looks chalky. We tried the vitamin pill check but no impact. The pool manufacturer sent us pictures that show a drained pool and workers sanding the pool to remove mineral deposits. They have not been on site yet to inspect and confirm but asked us to test sand a spot with 220 grit. Nothing changed. Looking for help and suggestions.