This is quoted from the link .
"Calcium is important for cell division and its deficiency is characterised by distorted new growth and weakened stems. New leaves have a twisted, bubbled appearance and edges can become necrotic. Old growth is not affected as calcium is the least mobile of elements. If calcium is deficient during fruiting, plants may develop Blossom End Rot, with sunken, necrotic patches developing at the blossom end of pods.
An application of CalMag (Calcium Magnesium feed) can help but it would be unusual for there not to be sufficient Calcium in garden compost, it is more commonly a problem of nutrient lockout. Excessive nitrogen and/or potassium hinders the plants ability to take on calcium, so check you are not feeding excessively.
Calcium deficiency can also be the result of low transpiration. If your pots are continually dry, this could be contributing to the problem and you should alter your watering regime."
This is a good site to bookmark, it makes it easy to figure out problems.
https://www.worldofchillies.com/grow...ientguide.html