New grower problems only with Purple Kush strain seedlings

[Cookies]

Im a relatively new grower got myself some nice beans popped a couple now my green crack some out perfect green looking nice even bigger then the purple kush, the kush both seedlings started a week apart have yellowing of the veins and browning tips on some of the old leaves i started feeding some calmag as i was feeding epsom thinking it was sulphur deficiency with no luck, plants hav been feed 200-400 ppm ph perfect solution so far, have been sprayed with some neem oil mixed with insecticidal soap, growing in coco under 300w mars hydro LED, Big plant is about a month old and smaller one is a week or so behind.

 

[spankegti]

What type of soil are you using? Have you check the run-off ph/ppm?

 

[Cookies]

Hey as stated growing in coco mixed with some perlite aswell, havent checked the run off for ph and ppm but i had just fed them some 1ml/L calimagic and my water starts at 70ppm, i just found it odd my green crack are fine both times just my purple kush did this?

 

[spankegti]

Sorry my bad on missing the coco. Looks like over nutes maybe the kush strain is more sensitive to them then the crack. Water with cal mag and no other nutes should turn them around I'd think

 

[Cookies]

Awesome thanks spankegti, I was already doing this so ill continue on how long should I feed only cal mag for? I'm also starting a PK seed and popping her into soil as well. Have not grown in soil yet but from what I've heard its a softer way to start your seeds because you dont have to add ferts right away? just to try and eliminate some factors

 

[spankegti]

Probably until they have shown signs of improvement and stabilized. I've never grown in coco but have had good luck with happy frog soil in my current grow