HELP! Purple Stems/yellow new growth, NOT PH! STUNTED BAD!

Ok guys, I have been growing in 2 different mediums with the same problems for months now and am begining to think that I just cant grow cannabis. I have 3 mothers in 10 gal pots of super soil and I have a tray of babies in pro mix HP. The pro mix babies are getting botanicare pure blend pro grow and cal/mg almost every feeding (every 2-3 days) I am only feeding half strength (7.5ml/gal and 3ml/gal of cal/mg) My plants always start out great but as time goes on in veg the new growth starts to become very small and spindly and turns a yellowish/lime green and is very stunted. The stems are also VERY purple. PH DOES NOT SEEM TO BE THE PROBLEM. I ph to 6.0-6.2 for soil and 5.7-6.0 for the pro mix, just tonight I flushed everything with plain phed water. They are getting plenty of nutrients and cal/mg and if its not a PH problem I don't know what to do! Seems weird that both mediums feeding or not I am having the same problem. Pics below I am stumped.

You've taken the PH of your water you're putting in. What's the PH of the water after you water the plant? (Place a tea holder under and get the water and ph it. Report back. Also how much are you watering?

Never used pure blend but your feeding too little phosphorus and likely lacking zinc. Might be a lockout caused by too much calcium.

The purple stems make it sound like it might be potassium deficiency. Potassium can get locked out by PH or by low temps.
What are your temps running?

Edit: if I remember right too much calcium can also lock out potassium. Are you using tap water high in calcium?

They arent rootbound are they?

I doubt its potassium. More likely phosphorus.

I'd think they would have to be. they look a little too big for solo cups.

1itsme said:

I'd think they would have to be. they look a little too big for solo cups.

Click to expand...

Ding ding ding... we have a winner.

Transplant. Compacted / rootbound medium will lockout phosphorous.

They are rootbound to the cups. The plant is indicating a definite Phosphorous deficiency and possible nute-lockup and nute-burn because the container is too small and the nutrients are burning the roots.

Transplant the plant, flush it with plain water, do not fertilize/feed for 1 week until the plant recovers then begin feeding at 1/4 strength and go from there.