I don't do hydro nor coco, but:

Do you spray the plants with anything?
Are there adequate drainage holes, or is the rootball sitting in water at all?
What is your ingoing water ph? Coco requires a lower water ph than soil.
Perhaps you bent/folded some roots during transplant? What do the roots look like now? (pop 'em out and look) Should be healthy white.
Why did you add a "heavy" dose of CalMag? Too low of a ph level can lock-out calcium, and magnesium is a salt. (coco retains salts)