In Europe, Calgon powder now contains zeolite, no mention of phosphate:
To remove hardness from water I add 1 teaspoon of this to a gallon or 5 L tapwater,stir well,allow the resulting suspension (zeolite?) to settle overnight.The mostly clear water now with no calcium hardess is decanted to a container.
To confirm hardess removed I added potassium carbonate solution,it gave no cloudy calcium carbonate precipitate whereas untreated tap water does give cloudiness.
IMO this type of Calgon powder should not be used in old formulas calling for Calgon,it would likely form a cloudy suspension.