Anyone have any ideas on what is causing this?

[Matteo21]

About 5 inch tall youngins in soil I do not have a ph meter so I dont know what that is. I added small amounts of veg nute (1/4 strength)

 

[namvet]

Looks like nitrogen def,but plants this size should'nt have this .I can't tell if all the leaves have this ,or just the bottom ones I would remove the bad ones and wait and see if your fert helps,make sure your not over watering, and make sure you have proper air circulation with a fan. It could have other problems but this is all i can come up with.

 

[mr.sessemia]

you need more info,..but it appears to be a Ndef..even tho itz uncommon you can have N def during flower...and your gonna want a p.h meter...if you seriously wanna fix the problem

 

[JM]

yup... ph is out... you need a meter looks like potassium / phospho def.... like high ph to me.... bet your water ph is high

 

[mr.sessemia]

yup... ph is out... you need a meter looks like potassium / phospho def.... like high ph to me.... bet your water ph is high

i agree wit j/m those spots on the laves do look more like cal/phospus def...........