Brown spots on lower leaves of young plant vegging in soil/coco/perlite

[ItsAllMedical]

It's the only plant that looks like this, although some of the other leaves have the light green margins like this one does, only more pronounced.

 

[ItsAllMedical]

Leaf of another plant, no brown spots but margins are yellowing. Potassium deficiency/lockout? It's lower leaves only so not calcium.

 

[mysticepipedon]

Looks like Mg deficiency or lockout. What's the pH?

 

[ItsAllMedical]

Looks like Mg deficiency or lockout. What's the pH?

Thanks, don't know at this point. I've got a cheap tester somewhere, but as I usually mix up a super soil & go for it I don't bother much with pH unless something starts to look off.

 

[lvstealth]

Grab some nature's living soil concentrate and add about a cup to the top and water.

 

[ezenzyme]

Are you feeding it anything? pics of the whole plant would help