You should be able to clean off the yellow with some concentrated acid. WEARING RUBBER GLOVES, soak a rag with muriatic acid and quickly wipe off the white fittings.
Salt with iron are only the granular salt with YPS (yellow prussiate of soda -an anticaking additive, contains a trace amount of iron). There is virtually no staining potential with solar salt or water softener salt.
Do you have a heater?

FYI, white return jets will discolor with improper usage of any other form of chlorine too.