Critical Fast CBD

This looks like a common problem most coco growers encounter. Keeping magnesium in your medium is hard with coco because if not properly flushed at the start with high magnesium, the coco will continue to pull magnesium out of your water till all the ionic bonds are filled. Increase your CalMag by 25%. If the problem persists or gets worse, double the dose of CalMag. I hope this helps.

Increase your dosage of cal/mag. Cal/mag deficiencies when growing in coco are common.