so first of all, she looks good out of the ladies, I'm not convinced it's a calcium deficiency... looks more like it's burnt in.... like condensation burnt in from light// heat, you had a heater on... but it's no big deal to add a little calcium + magnesium to the plant—there's usually nitrogen in it too.. so just be a bit careful—as long as the issue doesn't spread, everything is fine
Green Buzz Liquids has an organic calcium/magnesium product without nitrogen.