I've heard that fluctuating pH can cause symptoms that look like that.

Looks like Iron deficiency or possibly Zinc due to higher PH levels. I could be mistaken but I think Iron gets locked out when PH is around 7

Depending on your tap water, you probably don't need calmag. Are you adjusting the pH of you water before giving it to the plants? How are you measuring pH? PH fluctuations can cause the interveinal damage you see. Do you water to runoff? You are adding salts to your soil, you should be watering to 10-20% runoff to remove unused nutrients.

NorthernOrganics said:

Depending on your tap water, you probably don't need calmag. Are you adjusting the pH of you water before giving it to the plants? How are you measuring pH? PH fluctuations can cause the interveinal damage you see. Do you water to runoff? You are adding salts to your soil, you should be watering to 10-20% runoff to remove unused nutrients.

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I have not been adjusting/testing the pH lateley. When I do test, I use test drops comparing to a color chart. I do water to runoff. From this point forward, I will test and adjust pH of the water to 6-6.5 before watering.

I would feed them

Madbud said:

I would feed themView attachment 1240870

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Careful. There is a key difference between what's pictured in @retiredrob's pictures and the magnesium deficiency pictures above. Note how in the pictures of the magnesium deficiency the discoloration extends all the way to the edge of the leaf, or the margin. But @retiredrob's pictures show discoloration not extending to the margins and remaining only in the lamina.



Here is another picture showing symptoms thought to be due to PH flucations. Again, note how discoloration extends not from margin to vein. But from vein to margin. Staying mostly in the lamina part of the leaf.



I agree with those who suspect this is due to PH fluctuations. Likely on the high end. I used tap water for over 8 months without problems. Then at some point, the PH rose and it started giving me problems. I've been using Hades Down from Nectar For The Gods and it's helped balance things. I also started inoculating everything to increase my microbe populations. Currently having luck with Dynamyco and Oregonism XL from Aurora Innovations. It has helped with some of the sensitivity I experienced in the past.