Nutrients?

Salt burns, water used to transport nutrients accidentally sends fragments of salt if the medium is overfilled with salt. Salt gets trapped in epidermis where it burns surrounding chloryphyll.

Hi, definitely check your pH level... With the wrong pH level, your plant can't absorb calcium and magnesium = nutrient blockage We're having the same problem due to a faulty pH testing device. We've now adjusted the pH level in the water and "flushed" the ladies with about 4 liters of adjusted water. Additionally, we're now using calmag nutrients. Best regards and happy grow!!

Check your pH. Keep it between 5.8 and 6.4. That's the start of what looks like a Calcium deficiency. The question is, why? Out of range pH? Lack of supply, or Locked out due to too much potassium, or salt built up in the medium. If you are growing in Coco and you aren't using a specific calmag additive along side your nutrient line, i suggest you go get something like General Hydroponic's Calimagic, or some other calmag additive. Every nutrient line has one...take your pick. And if you aren't adjusting your pH when you water, and have no ability to, then you need to get yourself some sort of pH tester so you can setup your water before you water in.

calcium