Basically, I am making bubble bars for myself using surfactants that don't irritate my ridiculously sensitive skin. They bubble really nicely in my soft water, but I wanted to send some up to my mom who also has similar problems. Her water is really really hard (so much so that when I moved down here away from home I kept using waaaay too much dish detergent and shampoo etc.) so I was thinking I needed to add something to make the bars bubble in her hard water or it will be a disappointing bathing experience. Is EDTA the right thing for this purpose? I thought if I added it dry, it may be grainy as bubble bars usually feel crumbly and smooth when you break them into the running water and also wondered if it was the right thing to help in this situation?