Athosanswered grow question 7 years ago When your water source has low EC/PPM, it's a good rule of thumb to increase it to 0.3 to 0.4 EC/ 150 to 200 PPM before the nutrients.
200mg/lt of Ca plis 70 mg/lt of Mg is equal to 270 PPM of Ca + Mg, so yeah it should be more than enough, assuming what you are giving is in a form that's readily available to plants to take.
Although this late it won't make the symptoms go away it should prevent their advancement.