Alrighty sir! Ro water with normal nutes for the new grow
! Also the old stunted seedling is recovering but it has a few yellow tips on new growth and a mark on the new leaf. Maybe ph is still a little off so water till run off next time aswell? Also ive figured that salts buildup in coco and coco has Ph imbalances so water everytime till run off at 6.0ph?
There is Calmag in your nutes already. Try setting up a grow as Arthur has suggested and see if you get a Calmag deficiency, if not then keep on growing! If you do, then do what you can to stop it.