Why do my seedlings have light green or yellow veins?

[Owensteve85]

Every time my seedlings, have light green leaves with yellow lines in the veins as shown in the image.

1st week Water is ph5.8 EC0.4 PPFD
PPFD 150~200 24h

2nd week Ph5.8 EC0.6 (N6-P6.5-K19)
PPFD 250~300 18/6h
Humidity 60 ~ 70% Temperature 21 ~ 24C degrees. In this state, what do you think I am doing wrong?
Why is this? Please help me.

 

[crucialbunny]

More often than not yellow veins are a sign of a magnesium deficiency. You could try adding a small amount of Epsom salt to your water.

 

[GroBuddy]

Looks like a immobile deficiency maybe iron. Most do favor magnesium deficiency however this one does not

 

[NuggetMan]

Basic nutes needed here AND add some Cal-Mag. check your soil, may be lacking in the necessary nutrients. Especially in veg, they need nitrogen to be nice and green.

 

[Owensteve85]

Thanks for your advice.

 

[Owensteve85]

Thanks for your advice.