I think this is great advice honestly. I'm all for defoliation in veg, not a fan of totally stripping plants in flower. Striping some fan leaves will open up more bud sites, and allow more air flow. If the new growth is coming in healthy you might have already fixed it, and don't need to change anything else. It takes time for these plants to react, so its good to take your time with them.
I also agree with this. Lockouts and deficiancies can be hard to tell apart some times. Your water doesn't sound terrible but as high as it is I bet it already has a lot of calcium in it. So adding more calmag on top of that on top of whats already in the soil might be overloading the plants system.
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To much K can prevent mag uptake even if there is plenty of mag. Temps can be off preventing uptake of a nutrient, which then causes an issue with a different one................
I like Johns suggestion to defol and give it a chance recover before flipping. Once you start seeing some strong growth again flip em and keep them happy.
This chart and these comments have me focused. Like many things I didn't study it hard enough the first time. I've read about every deficiency and excess but not how they antagonize each other. Yup this looks like a key.
Assume I am right I see Mag def signs.
If I add calmag+, I add nitrogen, calcium, mag and iron.
The added nitrogen further increased the need for Mag. The added calcium increased the need for mag. The higher level of mag, even if locked out would increase the need for P. After a few cal mags i saw slight purpling a few plants leaves.
I can likely assume P is ok, it seemed to be before.
According to the chart only Ca or K can cause the appearance of my mag deficiency - not P. That assumes I had only be using water no additives.
My tapwater has a 3 to 1 ratio of cal to mag. Theres plenty of both, seemingly, in my lime in the mix. The ratio mirrors calmag solution so how far off can either be as far as availability.
If i could increase only Mag, it could only antagonize K, which if your suspicion of abundance is correct, would be helpful. The increased need for P would potentially be created by this also.
There are potential signs of sulfur def as JD said. The result of sulfur toxicity is slow growth...not a problem so far except one plant and it is not typical of the rest.
I believe the solution then is Epsom salt. It will increase Mag and sulfur. It will only potentially cause a problem with P.
Instinct and logic says this is correct. I had perhaps the right problem identified but have used the wrong solution.