How much calmag would you suggestion on week old seedling?

Week old seelding. Just barely starting to form second set of true leaves. I use coco/RO so it has nothing in it.

How much calmag should I add? I don't plan to add nutes until end of second week. So I want to feed it with some cal-mag this week. I am thinking 50 ppm. Thoughts?

NONE Seedlings dont need to be feed. They only use the light when they are in seedling stage.

Ya I'd wait until you add nutes before you start using cal-mag. And once you begin nutes with most nute systems you don't usually need full strength cal-mag. Through my entire grow using full fox farm nutes and others things, I rarely use full strength cal-mag as your nutes and other additives should provide some as well. I peak use of cal-mag products in early-mid flower. All other stages it's usually half stength or less. With RO and coco you will need to use it every watering at some point. If you do fed early fed 1/4 strength.