Supplement CAL MAG ?

Calcium deficiency shows on newer leaves, not older ones so it is not that. It looks like a textbook magnesium deficiency, but there's a few thing you need to keep in mind before rushing to buy cal mag or similar. First magnesium absorption is locked out when you overfeed potassium (K) or phosphorous (P) (flowering nutes) so be sure it is not an issue of overfeeding; also magnesium deficiency exists 4 to 6 weeks before it shows like in your pictures, so it will take a while before it looks like it is getting better. Your source water needs to be around 0,5 EC (250 PPM), if it is much lower, then you will have to supplement calcium and magnesium.