From what i can see in your photos, the growing medium is coco with perlite, i suspect you have not buffered the coco firstly, prior to planting, so they will die unfortunately, because they have a calcium/magnesium deficiency
Firstly you need to remove the fine coco peat from the coco,thoroughly flush the coco through a collander/sive, and let run off go into to a flower bed with a hosepipe,if your going to do it inside rinse over a bucket with a shower attachment do not let run off go down the plug hole/ drain otherwise you will end up with a blocked drain.
Once you have removed all the fine crap from the coco peat, then i get a 30ltr bucket fill with RO water at Ph 5.8 and add 2ml Cal Mag per Ltr, so 15ml and place your coco inside a old pillow case and leave to soak for 24hrs.
I do this twice, then i flush with pure RO water and make sure the run off is about 100 micro siemens,then your are ready to put plants into your medium.
Seedlings should be fed around 300-500 micro siemens, then crank up slowly.
Generally feed a day, nothing, water, nothing, feed etc, always leave a day in between for the coco to dry out a bit, before either feeding or watering.
Hope this helps.