Ratleanswered grow question 3h ago cal/mag would show yellowing between the leaf veins first and on new growth, you have leaves down at the lower part of the plant with yellow edges. If magnesium, those upper yellow leaves would already be turning brown by now for it to have spread to older leaves. Potassium deficiency starts with the edges of the leaves turning yellow and curling or twisting of leaves, that's what I see going on. Good luck