Need help identifying a problem

I don’t know what is going on with my one plant that is in a 50/50 coco spangham peat moss mix that is a mix of dry amendments. The ph of the water goin in is always a little under a 6.5. I have two other plants in the same soil mix with no issues. The yellowing is on the tops between the veins on the edges and a few tips. It is 3 weeks into veg.

Is it the same strain as the other 2 healthy plants?

I may be wrong but that looks like the beginning of a Potassium or Magnesium deficiency. I've never grown in coco so you may want a second opinion from someone else.

Did you switch lights recently?

Frank Warthog said:

Is it the same strain as the other 2 healthy plants?

I may be wrong but that looks like the beginning of a Potassium or Magnesium deficiency. I've never grown in coco so you may want a second opinion from someone else.

Click to expand...

It is different from the other two strains. I was Leary to diagnose as a magnesium because of where on the plant it was. Maybe it’s a ph issue causing the potassium to be locked out.

Herb & Suds said:

Did you switch lights recently?

Click to expand...

No I have been running the same t5 as before but it has grown a lot closer and is within a foot of the top of the canopy

Also maybe it’s potassium deficient because I took this cut from a flowering plant and it’s using a bunch to finish revegging

Peat moss sucks ... It gets compact when its wet and is very acidic. (This is coming from past experience)
Try using a coco perlite mix instead, you will have less issues in my opinion

Lower leaves look like a slight N toxicity and you might possibly have a lockout resulting from that or overwatering. That soil looks very moist, let it dry a bit.