3rd Bio Grow Super strain mix

I see that you're using soil, which retains nutrients much better than coco or perlite. Probably cut back on nutrients and use pH neutral water to 6.5 for a day or two. Then I'd do nutrients every third or fourth watering, slowly building back up. It does looklike the plants are getting burnt, but I'm also no expert. Cheers, and good luck!

Rusty leaf tips like that are a sign of potassium (k) deficiency , a calcium deficiency would be brown spots on the leaves.