FWIW, Chris emailed me back today,... He says cal-mag or other supplements maybe needed if you drop V+B levels. So, I might add magi-cal when I drop EC next time. I don't want to keep N levels high by adding more V+B in the last few weeks.
I've started trying a small mound of Epsom salt under the dripper from the Blumat to try and take care of this. I don't understand why the plants seem to go into a variety of deficiencies rather than just staying in balance and wanting more food.