Raise the ph to about 6.2-6.5.. its possible thats ur problem to low of ph, but thats easier to correct than high ph... just adjust the water a little. its not shock or anything to the plant of that little of a change but try raising it just a tad and see what happens. imo get the ph of the run of to find the problem and then aim for the next watering to be around 6.5 if the ph of runoff is lower than 6. ur aim is maintain 6.2-6.8 in soil
lower in hydro..