Good stuff.My ppm of the tap water I use before adding anything to is 150ppm that after it sits out for a day or two. I have started a foliar spry with cal/mag plus botanicare 1ml per litter ph to 6.3
Don't go overboard with the foliar misting. You can burn the leaves. One or two applications at the affected areas, then stop spraying while continuing to add Cal-Mag to your nutrient solution at about the same level as you stated you already are (my water is 55-65 PPM and I use 4.5mL per gallon, just slightly more than you're using).