What is wrong with this seedlings???

They were planted 14 days ago... but tap root was a little bit dry, i rehydrated them and when tap root looked good and hairy planted. they had it difficult to create a good root system it looked and when i transplanted from solo cups to 1/2 gallon pots some 4 days ago the one in the left had roots but only a few and short... the two in the right better but not 100% healthy. one is already showing roots from the bottom holes of the pot so i assume slowly their roots are growing and becoming healthier. the problem as you can see is not only that they are understandably growing slowly but that they are turning yellow and have burned tips and edges...
i have watered last time three days ago with tap water like 280pp with just a little GH FloraGrow( like 1/4 strength) total was like 310ppm on 5.8pH. What can it be??? lights are some led cobs which i moved away even more from the plants. Can it be light burn? Nute Burn? or something else??

Seedlings only need tap water and your medium is too dry

Damage from light would look more like bleaching or white leaves. A lot of air flow and low humidity could burn your tips but it's probably something goin on in the root zone. What medium are you using? Coco is good at ph5.8 peat ph6.3. Get ro water and you will be good.

Even 310 ppm can be too much for the little plants. Just give them water for now. They also look a little dry to me. Just my 2 cents.

gardener60 said:

Even 310 ppm can be too much for the little plants. Just give them water for now. They also look a little dry to me. Just my 2 cents.

Click to expand...

Exactly

Thanks for the input...
it was watering day today, i watered after taking some pictures.pH 5.7 and runoff was 450
personally i thought to about nute burn...if this continues i might flush with ro water...
for the moment they are in 100% coco.