Day 30 flowering/some plants yellowing

Hello I have yellowing problems on some of my plants....
Im on 30 day flowering, started from clones. 6 plants vegged 3weeks 8 plants vegged only 1week. When they rooted well, transplanted them in Bio bizz All mix. The 3weeks vegged are in 3 gal pots and the 1week vegged plants are in 1,6gal pots...
All smaller (less vegged) plants are looking healthier and greener... Idk why...
I water them every other day with half gal of pure water, started to add nutes @ 15 day flowering.
Im using GHE Flora 3 part series with all aditives suggested (like mineral magic,bio bloom,bio roots, bio protect, diamond nectar + im using cannazyme to)
I wonder why some of my plants are starting to yellow but others are still exploding green???And they have same watering and nute dosage. I'm sure that the Ph is not the problem here, because all the plants will suffer the same thing, i belive. Anyway my tap water is 120ppm and 7ph stable all the way.Im not using any ph corrector... Think i dont need...

Can be heat stresss (i CANT feel any heat with my hand under light above canopy)? ....
Or under water problem...?
The healthier plants are directly under fan and mostly under LED light, the worst looking are directly under cool tubed 400w hps and farthest from fan...
Grow room temp is about 77F-82F lights on, around 68F when lights off and RH is around 55% all the time.

Greensea said:

some of my plants are starting to yellow but others are still exploding green???And they have same watering and nute dosage

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each plant is different, even if they are all from the same mother, the genetic make-up always differs in small ways, some plants will eat more nutes than others.

Awesome grow there dude! Very nice btw

What do you think of this yellowish girls. They need to eat or are just unhappy for some other reason, and which reason if you know ... I mean ... how could i can make them happier...?
It's a medical strain not so grateful with weight but nice taste and smell. 14%THC/12%CBD Sativa 60%/Indica40% 9 week fowering....
Im at half flowering atm.
I just measured the runoff Ph and it was 7.6...
Think i need add some ph- till to 7.0

Greensea said:

Think i need add some ph- till to 7.0

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yah sounds like a good plan, definitely lower ph to 7 or maybe even 6.5.

halfway thru flower cycle u say? then time to add a little P and K if u haven't already done so

"...I water them every other day with half gal of pure water......"
stop. let them dry out between waterings.

DonAlejandroVega said:

"...I water them every other day with half gal of pure water......"
stop. let them dry out between waterings.

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agreed. that sounds like a LOT of water.too much.

plants in the last three pics look nitrogen deficient. nice looking grow. GL

Thnx for reply guys!
Ok than i need to less watering... and maby got N deff...<--- leave it or try add at this point??
Yea im at half flowering right now... so u think is time for P/K boost? although i use GHE 3 part series?
In the last two weeks I intend to watered only with tap water...

calmag def

Hmm...calmag def...?
Even if im using Ghe 3 part series nutes?
Can maby to much watering cause calmag def. by lockout ?... or somethink like that?