Photoperiod yellowing leaves

[Trichome farmer]

Problem: fan leaves yellowing

Medium/grow method:
plagron coco and perlite
AUTOPOTS
1.2m x 1.2m tent

Feed: and supplements used:
canna a+b coco
canna boost
cannazym
vitalink cal mag
vitalink root stim
big bud coco
vita link ph down

water source:
well water ph 6.2-6.7 EC 0.3

Strain/age: white widow x black domina start of week 4 flowering

light used: GN telos 008

Climate: 18-26c 60-85% RH
small dehumidifier
16inch mounted fan
4inch extraction 15 mins on 15mins off etc.

Additional info:
not sure whats causing the yellowing im thinking its humidity certainly some of the damage is from the RH but im not sure about some of them maybe im going abit light on the feed but also i started them on the rez on week 3 and have been having trouble keeping the ph in the rez between 5.5 and 6.0 keeps drifting up to 6.2 6.3 do i just keep adjusting it back down with ph down solution how much is too much

humidity?

???

humidity?

 

[Waira]

Hey bud! So, what's the ppm's been like in the res'? Also, coco doesn't need to be as low pH as hydro, upper 5's-low 6's is fine, so it might be the lower pH was starting some lockout...
Symptoms look like early K defc., not sure if from the pH issue (less likely, K is pretty robust in availability across pH), and/or caused by the poor VPD screwing with transpiration, slowing nute transport,....
What is the light sched', and when is it 85RH% in there, during lights out? If so, maybe something else in play, since transpiration slow to near nothing during dark (no C fixing going on then, i.e., photosynthesis)

 

[Trichome farmer]

Hey bud! So, what's the ppm's been like in the res'? Also, coco doesn't need to be as low pH as hydro, upper 5's-low 6's is fine, so it might be the lower pH was starting some lockout...
Symptoms look like early K defc., not sure if from the pH issue (less likely, K is pretty robust in availability across pH), and/or caused by the poor VPD screwing with transpiration, slowing nute transport,....
What is the light sched', and when is it 85RH% in there, during lights out? If so, maybe something else in play, since transpiration slow to near nothing during dark (no C fixing going on then, i.e., photosynthesis)

thanks for having look waira the e,c has been 1,4 or 980ppm pushed up another bit yesterday it stays the same due to it not be recycled
and i never drop the ph lower than 5.8 if possible and tends to rise to around 6.3 would you say this is acceptable in coco
yesterday i mixed up 20 liters of water ph 5.8 it has climbed to 6.3 anything i can add to the rez to keep it more stable or do i have to keep adusting with ph down can i add to much ?
the RH hits the high numbers lights off (12/12) never gets above 70 lights on
is it possible im just not feeding them enough it does seem to be older leaves its affecting rather than the top new growth iv been trying to play it safe for my first grow after a nearly a year off

 

[Waira]

pH can be irritatingly dynamic! Your water is good, enough EC/ppms of hardness (well assuming that actually, CaCO3 hardness that is; well water can be a tricky mix unless a chemical analysis is available)....so there some buffering going on there....
yes, when lowers are affected, it's a mobile nute being tapped into, like K... maybe look into their PK 13-14 and see if that helps,... uppers not showing any symptoms, not tip/margin burn?