Leaf problems

Hello I'd agree that its probably calcium, some plants are extra calmag hungry so you could try to raise it slightly...either .5-1tsp per gallon, or increase the frequency you use it instead of the amount. Or you can use dolomite lime which breaks down over time. A couple other things can block out calcium like having an acidic soil(less than 6.3), excess potassium can look like calcium problem also. But definitely keep in mind that any damaged leaves wont heal even once the problem is fixed, you'll have to watch for no other leaves getting it.