CalMag deficiency?

Not a deficiency of any sort...........this is burning caused by a salt build up in the substrate. Generally occurs when people irrigate incorrectly by not getting adequate run off each time they irrigate and only water in small amounts near the stems in some sort of strange fear for "over watering". Overwatering is watering too often, it is not not watering deeply and to run off. Cal mag will not solve this issue.............make sure to get 10-15% run off each time you irrigate to prevent it getting worse, but the build up is already there.........you can only prevent it by watering properly for your entire grow........right from seedling stage. Do not "flush" or try any other sort of weird treatment, these can often cause more problems than they solve. Plain water for a week should help reduce symptoms...........but you must always get run off............then resume feeding gently.

The leaf Symptoms to me looks like a dificiency with magnesium. Did you check ph in drain? Do you know your water? Cal/mag relationship is set right? 3:1? Sometimes a cation antagonism is the problem if you overuse your nutrients.

Heh ) this is a treaky one 😏 Looks like Ca for sure, but i think it's not that more likely it's a B,K,P and (also Mg ) lockout I need to see the base of the stem to be sure on 100% but without it i'm sure on 80%

Could be a few things: since it always happens in the middle of the canopy, it really sounds like a pH issue – nutrients are present but can’t be absorbed properly. Cal/Mag especially gets locked out quickly if pH isn’t in the sweet spot (measuring the runoff can give you good insights). Too much CalMag can also push out other nutrients, so watch out for overdoing it. Spots starting in the middle of the leaf and moving toward the veins often point to a deficiency caused by pH lockout or an unbalanced feed. Light intensity in the canopy center could also play a role. My tip: check your pH carefully, keep CalMag moderate, and see if symptoms stabilize. Happy growing & good luck! 🌱✌️