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Calcium deficiency on the right and magnesium deficiency on the left.
Underfeeding may also present as a cal/mag deficiency as well.
There are very good ways to rule out cal/mag deficiency if using tap water, basically if you can ask or get hold of the water analysis results from your local water supplier they will detail calcium and magnesium. Results are often written in either ppm or mg/l. If there written in mg/l i can change them to their ppm values.
Calcium to magnesium ratios generally need to be 3:1 for the whole grow although Sensi and others recognise the plants higher needs for calcium in vegative stage and magnesium in the flowering stage so the recomend a ratio of 5:1 cal to mag for veg and 3:1 cal to mag for flowering.
The approx amounts generally needed in water are around 90ppm calcium and 30ppm magnesium, which would give you a nice 3:1 ratio. Any more should not be harmfull but might affect the ratios.
Calcium is uptaken by the plant passively, the healthier the plant the more it drinks and the more calcium it needs and uptakes, unless chelated and then it can be transported and uptaken actively through the phloem not passively through the xylem.
This is just a simplified veiw but should help. Peace