So possibly locked out. My outdoors did this last summer. I flushed with about 5 gallons of water. Waited to dry then resumed nutrients at required amounts. The darkening to me, looks like phosphorus deficiency and the yellowing looks like nitrogen deficiency.
5 gallons of water for a medium/small plant?
No probably not. Are you checking ppm #s? You want to get it down where your runoff is pure water. Basically rinse your soil back to its base. I was in 10 gallon pots.
Ok, got it, I am using 5-gallon pots
Thank you 
I would get some runoff numbers. Feeding to run off helps rid any salt build up. It’s out with the old and then with the new every time you feed to run off.
If you’re feeding your girl sensei by advanced nutrients you’re more than likely not locked out
Advanced nutrients coco sensei is chelated. (Almost impossible to lock out) Also please note, you NEVER pH adjust your feed/water basically your pH is totally irrelevant.
The special chelated formula advanced nutrients uses allows your roots to uptake nutrients at much lower and higher pH levels within your coco. This is why you never pH adjust your feeds when using sensei. Adjusting the pH can actually hurt.
Enough said on that.
I’m assuming these are photo plants better 2 months old an extended veg am I correct?
I’m not very experienced in Coco nevertheless, 2 months old you should be feeding them girls all the time and getting run off numbers. Having runoff assist you in knowing how much nutrients are in your coco. These numbers will dictate how much you feed.
I love you!!! I am sorry for the late response; I have been busy.
You got everything spot on.
Now, Sensi nutrients, THAT is what I was told, what I read, what I knew! No need to check PH! But then my ex: “checked the PH after I put nutrients, and it was off”, and indeed it was; we thought the PH stabiliser worked jn hydroponic,
Now you are telling me this 
, 
, but thank you, truly, for taking the time to explain it, I knew there was more to it.
Why was my PH off?
Is it because the PH pen is not accurate if Sensi is present?
Much obliged for your help
I’ll give you the short version. Your runoff pH is not off nor was it ever. Forget what your Pen said
The chelation allows pH change throughout the soil/coco but also allows the roots to uptake the nutrients from levels as low as 4.0 to as high as 10.0 and everything in between. (That’s the short version)
As long as you’re using Sensei your pH is irrelevant. (Ignore it or don’t even check it)
Now if you want the long version to what chelation is (this is probably in the most layman terms)
Good luck my friend
They look mighty fine now 
THANK YOU EVERYONE WHO HELPED.
It wasn’t only this post; I had 2 previous topics for these girls and 5 more babies, plus an out-of-the-blue Autoflower!
I had a nutrient deficiency and underwatered them, and I thought maybe the problem was the pot size.
They now look good.
Here is the proof.
Thanks again, until next topic 
Ok, i got it, the values showed with the ph pen dont apply anymore, perfect!
I will feed them to runoff as you advised.
Thank you
If your pH drops below 4.0 or above 10.0 come back and see me
Roger That!!!
"Does Advance Nutrient’s "pH Perfect" technology actually work?
“It works perfectly. We use pH perfect sensi grow and bloom two-part base notes and we still check the pH anyway and it’s always right where it needs to be”
I found this quote as an answer to the question on top.
It says the PH, when measured, was always perfect.
Mine isn’t perfect when I use Sensi A+B; it’s always on 6.7 or above. Is that being “perfect?” because Coco needs a 5.9.
Sorry to be a bother
Says the 14-year-old kid from Reddit (on his first grow). .
As I stated many times above the key word is irrelevant you no longer check the pH (your pH numbers are irrelevant).
Note:
I can appreciate your skepticism. I’ve done everything in my power to break it down in layman’s terms. I can appreciate that you continue to search. I guess I’m not sure of the answer that you’re looking for.
My best advice, if you don’t feel comfortable or confident discontinue use.
Also, there’s an 800 number on the back of the bottle. they’re on West Coast time that will answer any questions you have regarding their products.
I wish you the best of luck!
I think I know where you’re getting confused.
You’re checking the pH of your runoff. You run off says 6.7 pH (and I’m sure that it’s correct) the pH in your coco is 6.7
You’re used to understanding that Coco requires 5.8 to 6.2 pH for proper nutrient uptake. (And you’re correct)
Your new sensei nutrients are chelated. (The video above if you want it) Explains the chelation process.
In layman’s terms
The pH perfect system that advance nutrients offers (chelation) defies the laws of pH nutrient uptake availability.
The chelation changes the availability pH value of nutrient uptake. Example iron normally cannot be available to the roots at 6.0. (you’re basically locked out) the chelation formula allows the nutrient uptake at almost any pH in your soil/coco.
The chelation basically masks every molecule in every nutrient that’s in that soil/coco allowing it to be consumed by The Roots at any pH level.
In short, do not compare the actual pH value of your runoff to the pH of a normal Coco runoff. It’s going to be irrelevant
This is the best 7th grade layman’s term I can come up with.
The video above that I posted yesterday explains chelation in more layman’s terms.
If you want the more scientific answer. Below is the founder of advanced nutrients pH manifesto it’s hands down one of the best reads you’ll ever encounter. It’ll give you the scientific answers that I think you’re looking for.
Trust me I’m only here to help you. Not belittle you or be sarcastic. I know most of this sounds too good to be true and you have no reason to trust me or anything I say.
You can rest assure one thing. I’ll never steer you wrong. I take growing very serious.
Stop checking your pH let the nutrients do their job. Below is a specific feeding chart for Coco growers utilizing sensei with milliliters per gallon breakdown equations.
Coco and soil are treated the same when it comes to feeding. The only difference Coco requires more feeds/waterings. You feed every time you water the coco.
You want to obtain and maintained a 1000ppm runoff each time you feed. +/- 200ppm in flower any conservative 800 to 900 PPM in extended veg for photo plants.
All the best to you
Ok, I am doing that.
Wow. Sorry, I have not answered before. I did not have time yesterday to read and assimilate everything.
Please don’t ever entertain the idea that I don’t value what you say, or, even worse, I think you are misleading me, your level of knowledge on the subject it’s undeniable, and i can only thank you for your help.
I am going to watch the video and read “The Manifest”, thank you again
Ok, I look at the picture and I read the manifesto, there is no video to watch
“your water is 30 PPM or below you’re safe”
@Lostgirl, I am reading a few things explained in the manifest I heard of, like the water alkalinity; my understanding, tho, was, "Get an RO water treatment if your water is over 500 ppm. Some say 300; please tell me the 30 value in the manifesto is 300.
Edit:sorry, I misspoke, water hardness, not alkalinity,
Edit 2, sorry again, Alkalinity is the important because just softening the water doesnt get rid off alkalinity!
Still my question was about the 30 value which i really hope they meant 300 ppm