Need help with this deficiency!!

Hello all. Couple weeks into flower notice brown spots. Indoor was using LED. Thinking it's a cal mag issue. I have been using RO water with no cal mag added. Looking through the forum thinking why im having this problem. Is it beacuase of no cal mag added to the RO water and the use of the led. Plants need extra cal mag under LED. Let me know what you think? Also have added some cal mag to water&changed to hps.

I had this problem early on but my stops were much bigger on each leaf, amazingly i didnt use calmag to stop the issue my temps were just way too high and no air circluation

It’s a CalMag missing issue - plant need it and it has nothing to do with LED lights

People need to know what fertilizer is being used and how often to help.

Calcium deficiency