Also, TSP, from Home Depot works well, too. Trisodium Phosphate is used by painters to clean walls before painting. Just a hair of it with the detergent puts back that phosphate. I keep it in a sugar dispenser to pour into the detergent reservoir.
Haven’t heard of it, but worth a try if it is not to expensive.
I keep a tub with a coffee scoop under the sink instead of the box, takes up less room. It could be pre mixed that way.