In soil you don't need to add cal mag with every watering if you are using tap water but you can't go without it if you are using reversed osmosis water . My thaught is that you are using tape water like 90% of us on GD so your water contain cal/mag , you soil have a bit of cal/mag inside or at least some mag ( they are always adding some mag in the soil , must be cheap ) , you have cal/mag inside your nutrients or at least mag so my guess would not be a calcium deficiency but it's not really looking like an excess neither . When I take a close look at some of your tips you can see that some are starting to be yellow or slightly burnt so may be a nutrient excess that created a salt buildup in the soil and a nutrient lockout for the plant. Flush your medium