DrJonesanswered grow question 2 years ago I think you might need some cal and mag. If your water is already high in cal and mag then I would lean more towards the ph of your soil being out of the ideal range which stops your plant taking up essential nutrients. Test the ph of your run off to find out. There has been times where I put it in at 6.5 but it came out below 6. If it’s not between 6.0 and 7.0 then you should try to balance it out next time you feed.
Good luck!