— Nitrogen deficient, as evidenced by how yellow the leaves are this early in Flower
— CalMag deficiency as evidenced by interveinal chlorosis (the yellow tiger stripes in between the veins of the leaves)
— Phosphorus deficiency (random larger brown necrotic spots on the leaves)
I’ve not used Jacks but it seems the majority of people here do and they all say full feed after a flush. Hope that helps 
Those issues using Jacks makes me think the pH in the root zone is off.
The nutrients are there but not being used by the plant.
Are you feeding every watering?
The Jacks people do feed every watering, yes
This is being addressed in another thread started by the OP.
I will move over there.
I know @pr uses Jacks. Maybe he can chime in. If I think of others I will tag them too
Good to hear. I’m unable to help 
Hence the flush to try and regulat whatever is going on there. But whatever they use in fox farm soil even after 24 gallons of water flush each pot. My ph always stayed at 6.5
Yeah soil tends to hold a pH. I think most of the Jacks users are in straight coco
So far, ive had minimal issues with jacks being fed every watering. I did have a ph issue recently with some coco i expanded, causing major seedling problems, and even losing a zkittles. Dont let the newly expanded, buffered, and ph’ed coco sit for days before using. @Low repeatedly told me to use it immediately after expanding, i blew it, and paid the price! Wont happen again😉
Thanks thats great to know! I just spent 60 bucks in coco and vermiculite. To the garbage!!
But you can rehydrate or rinse again, with proper ph’d nute solution, and roll on w it.
Ok makes sense. You had it preped and ready to go and you just let it sit there. You could have retreated and it would have been fine. I get it!! My first thought was wow i been hydrating and running distilled water through it for days and now it uselessness because i dont really need it till im done with this grow. But im clear now.
Always learning
I’ve been feeding Jack’s, mixed to at least full strength, sometimes over, since first day of feeding. In 3 gallon pots, 2 in Roots Organic 707, 1 in FFOF and they get fed every watering, 2-3 times a week. All are in flower.
And your plants never show any signs of nutrient burn doing so, ever?
@Low do you have better results from growing with coco?
I been experiencing plenty of issues with drainage. Im certain its a combination of the medium i choose and the grow bag i’m in that are causing me to be inconsistent with the drainage of a couple of my plants. Almost all my plants are doing well and are happy with the amount of water i give them but two of my plants aren’t draining well and it has thrown me off some on the amount or frequency of water i give them. My fault totally but i feel i wont have drainage problems and can water more frequently with out main issue of overwatering. But im sure i’ll have to stay on top of other problems that can arise from using coco
I get a little burn during flower because I bump it up, but nothing that concerns me.
Can you explain further the issue of preparing coco, that is hydrated with ph H2O and buffered (I use Cal-Magic), and then let it sit dry until needed.
I rinse and sieve my coco and do this outside when the weather is nice. I then soak it in pH’d H2O with Cal-Magic for two days. After that I dry it on screens to be used during the winter. Before using or transplanting into it, I rehydrate it with 50% Jack’s solution the day before. I use Canna Coco bricks and will do this with 2 or 3 bricks (40 - 60 liters of prepared coco).
@THC73 I gave vermiculite a try in soil and did not like it because it retained too much water. In coco I add perlite but Vermiculite may be worth considering. Not because of its water retention capabilities but more for its Silica.
I was reading about this the other day a potassium def can make the leaves go yellow aswell specially in flower
