Young plant, Yellow between veins of older leaves

[airone77]

Hello guys, been reading for sometime now but this is my first post...arrogant first post needing help
-Problem: yellowing between veins of older leaves, then they get brown, 10 days old plants
-Medium/grow method: Biobizz lightmix soil.
-Feed and supplements used: biogrow half of dosage three days ago, calcium magnesium supplement (only one feeding, 600 ppm)
-Water source: bottled water, 20 ppm,pH 6
-Strain and age: Royal Haze and Fat banana
-Climate: 21 °C, very dry 30% RH (first time ever that it got so dry)
- Light used: HPS 600W, 20 on/4 off about 40/50 cm from plants
-Additional info: it starts as a white discoloring between veins tip side, then it get yellows and brown starting from the side inwards

Thanks!!!

--Pictures:

 

[namvet25]

The one leaf looks like nutes got on it .Hold off feeding nute and just give her lain ph water for awhile and give her some calcium.

 

[Bob's Auto's]

Hello guys, been reading for sometime now but this is my first post...arrogant first post needing help
-Problem: yellowing between veins of older leaves, then they get brown, 10 days old plants
-Medium/grow method: Biobizz lightmix soil.
-Feed and supplements used: biogrow half of dosage three days ago, calcium magnesium supplement (only one feeding, 600 ppm)
-Water source: bottled water, 20 ppm,pH 6
-Strain and age: Royal Haze and Fat banana
-Climate: 21 °C, very dry 30% RH (first time ever that it got so dry)
- Light used: HPS 600W, 20 on/4 off about 40/50 cm from plants
-Additional info: it starts as a white discoloring between veins tip side, then it get yellows and brown starting from the side inwards

Thanks!!!

--Pictures:View attachment 1441142View attachment 1441144View attachment 1441145View attachment 1441149

to AFN buddy!!
It looks to me that your light is to close to those little seedlings. A 600W HPS light produces so much heat... You can leave it be now as probably the new leaves don't show these defects, right? That's because the plant becomes accustomed to the high levels of light.
Oh and dial back the nutes. The light mix does have nutrients in it. Just give only water for a couple of water gifts.