I see cal/mag deficiency quite a bit with the nutrients I am using and a little garden lime and Epsom have been great additives for it. It has always started toward the bottom of the plant. Magnesium deficient and in the leaf between the veins will lose color. The calcium deficient will get light color and brown spots towards the outside edge of the leaf. I find it takes a few days to a week to start to recover from it. Effected leaves do not come back much if it has progressed to browning. You need to watch the new growth to see if it is getting better. I will add a couple pics of them recovering from this shortly.
This is not exactly the same as what is going on with #2. It started mid plant the day after its first good feeding and is progressing very fast. To note, #2 is the only one that seems to be doing this. The rest seem quite fine. For right now I will do nothing but keep a close eye on her. New growth seems ok, but they all do have a bit of yellow on the tips.