Yellowing in Coco, I think I know whats wrong.

Hey there everyone.

I have been having an issue rear its head in coco recently, and having never grown in coir before I thought I better ask.

Anyway I cut and copied this:

HYDROPONICS/Aero Ponics/Coco/Soiless/

How long has this problem been going on? Ever since the plants were moved under the "big" lights
Are you growing in a PVC grow tent? Yes, but its not the problem, as I have had several successful harvests in this tent before
What system are you running? Hand Watered Coco
What STRAIN are you growing? Black Domina and Lavender
What was the establishing technique? Seed
What is the age of your plants? 5 Weeks since sprouting
How long have they been in there mixture they are in now?They've been in Coco since they were around 5 days old
How tall are the plants? 40-50 Cm's
What PHASE are the plants in? Veg
What Technique are you using? None
What substrate/medium are you using? Coco
What is the Water temperature? Um...Dont know...Tap water temperature?
What color are your roots? White? Brown? Are your roots slimy? Roots are big, thick, and white!
What Nutrient's are you using? Canna
How much of each nutrient are you using with how much water? Canna Coco A+B 3 Mils per liter, Canna Rhizo 2 Mils per Liter, Canna PK 1 Mil per liter
How often are you feeding? Everyday
How often are you giving nutrients? Everytime
What order are you mixing your nutrients? Base Nute first followed by additives
What is the TDS/EC/PPM you are using? 1.5
What is the pH of the "Tank"? 6.3-6.4
How often are you testing your pH/PPM/EC/TDS? Every night when I make it up
Are you sure your calibration is correct on your equipment? Yes absolutely I calibrate regularly
When was your last watering? Last night
What size bulb are you using? a 400 over the BD's and a 600 over the L's
How old is the bulbs you are using? New
What is the distance to the canopy? around 30-40 Cm's
What is your RH Factor(Relative Humidity)? Approx 40%
What is the canopy temperature? 25 degrees celcius
What is the Day/Night Temp? Night is 19 degrees celcius, days average 25 but can get as high as 29
What is the current Air Flow? Heaps
Tell us about your ventilation, intake exhaust and when its running and not running ? Exhaust is a 250 Centrifugal that splits in half and sucks through 2X150 cooltubes in the tent
Is the fan blowing directly at plants? No
Is your water HARD or SOFT? Very Soft 0.1 Ec
What water are you using? Tap
If using tap water, what is the ppm/EC/TDS of the water right out of the tap? 0.1 Ec
Are you using water from a water softener? No
Has plant been recently pruned, cloned off of or pinched? No
Have any pest chemicals been used? If so, What and When? No
Are plant's infected with pest's? No



Alright people so I figure this is one of three problems

1) Over watering. The plants appear to "sag" slightly and have yellowed like I have seen soil plants do when they are over watered. The problem with this thought is coco is supposedly unable to be over watered. I water ever night and the coco gives run off every night (run off Ph and Ec is the same as water going in)

2) Cal Mag deficiency? Ive never run coco before, however I know ALOT of people using it need Cal Mag. Ive heard though that big nute companies like Canna allow for Cal Mag in the water and it shouldnt be an issue unless your using RO? The plants have that yellow leave with green veins going on though which I believe is magnesium related.

3) Light burn (or whatever this is called). The plants started yellowing the moment they went under the "big" lights. I wonder if the 400 and 600 have bleached them a little. Although they were originally under a 250 so its not like they're not used to HPS lights.


Anyway heres some pics










Symptoms are pretty obvious. General Yellowing of plants. They're still growing nicely though, look healthy enough. The leaves on the BD seem to sag a little however they are great big fat indica leaves!

Anyway thank you VERY MUCH for any help!

Your PH is out & yeah Mg issue, certainly not overwatering or light burn. Should PH to more like 5.8 in coco. drop using the PK untill bloom too. i wouldnt dissmiss using a Ca/Mg supp either.
Plants requirments are gonna change when you switch to more intense lighting

i grow in botanicare brick coco 5 kg bails and from clone i feed 800 ppm of maxigro and 1 drop of H&G drip clean per gallon. nothing else! i feed that everying watering with no drains in my pots with no problems.

def looks light on food, plus your ph is def a bit off, and idk they seem over watered 2 me aswell... how often are you watering and how much run off would you think ur catching???

good luck!

also, i have noticed that some plants dont like coco in those grow bags, so maybe transplant to real pots... i bet if you cut that bag offf your insides/roots wouldnt look the best! get um outa that plastic

PK is locking out MG and are your lights too close?
I didn't notice any mention of runoff.

Definitely not light burn.
Looks like lock out due to PH imbalance. Please adjust your PH to 5.8 going in. I would like to know the runoff PH. Guessing it's high.
I would flush one of the plants with PHd water, then feed also @ PH 5.8 as a test. Guessing you will see immediate (overnight) improvement.

RetroGrow said:

Definitely not light burn.
Looks like lock out due to PH imbalance. Please adjust your PH to 5.8 going in. I would like to know the runoff PH. Guessing it's high.
I would flush one of the plants with PHd water, then feed also @ PH 5.8 as a test. Guessing you will see immediate (overnight) improvement.

Click to expand...

Not burn, but he mentioned high temps in his questionnaire.
Didn't notice his PH level there though. Good catch

i have never grown in coco, but to me it looks like a salt build up or ph issues, maybe you are letting them dry out so salt gets built up?


other than that i see N def, Ca def, Mg def, and P def...


the purple stems and leaves curling down(like from overwatering) is a sure sign to me of salt build up locking out other nutes...


either way i see lock out

Get In The Zone!

Get In The Zone!

Scrogerman said:

Your PH is out & yeah Mg issue, certainly not overwatering or light burn. Should PH to more like 5.8 in coco. drop using the PK untill bloom too. i wouldnt dissmiss using a Ca/Mg supp either.
Plants requirments are gonna change when you switch to more intense lighting

Click to expand...

Right on point def ph outta range and much much too early for pk. Plants aren't happy and your outta the coco zone per say I wouldn't drink if I didn't like what I'm being fed so yeah maybe over watered too.

joe fresh said:

i have never grown in coco, but to me it looks like a salt build up or ph issues, maybe you are letting them dry out so salt gets built up?


other than that i see N def, Ca def, Mg def, and P def...


the purple stems and leaves curling down(like from overwatering) is a sure sign to me of salt build up locking out other nutes...


either way i see lock out

Click to expand...

Stems can turn purple when underfed, underwatered or when really cold water is used. Another good catch though. He mentions he gives it to them out of the tap. My tap can come out really cold.
are you letting the chlorine evaporate? You also want the water Luke warm in containers.

TribalSeeds said:

Stems can turn purple when underfed, underwatered or when really cold water is used. Another good catch though. He mentions he gives it to them out of the tap. My tap can come out really cold.
are you letting the chlorine evaporate? You also want the water Luke warm in containers.

Click to expand...

true, my tap is 11 degrees celcius....gotta let it sit with circ pump for atleast 6 hrs to warm up....

the reason i said salt build up was because he said he hand waters, i heard if you let coco dry out the salt builds up....

also heard you need to flush coco before use to rid the salt buit up in it.... wondering if the OP did that?


then theres the salts from the PK booster that he has been feeding the plant which the plant def has not eaten, so those salts get left behind too....


ive had a few salt build ups in soil and thats what the lock out begins to look like but with more K lock out...considering coco is a decent source of K i figured thats why we werent seeing a K def...

im sure others said it but ph is too high probably causeing buildup.. flush and fix ph to 5.8 an all should be fixed...

as for flushing coco before use only need to do that if the coco was bricked not bagged.

Thankyou for the help everyone!

I will definitely drop the PH, I always thought a slightly higher PH was needed for Coco.

Im so sorry I said PK instead of Cannazyme, I was half asleep, sorry. I wouldnt be feeding PK in veg.

As for run off I get around 20% run off each and every time. It is always the same PH as water going in, and same EC as water going in.

I will up the nutes tonight to 1.6 and PH 5.8.

I water every day and feed every day.
Thankyou for everyones help!

Also I definitely flushed the coco thoroughly before use. I originally had them bagged in brick coco, and I rinsed that like crazy before use so I got an ec of 0.1 (same as tap water) coming out the bottom. Then when I rebagged them recently I used expanded, pasteurised stuff that didnt need rinsing.

I do evaporate the chlorine out of the tap water. It is cold, like around 15 degrees celcius.

A couple of people are saying it looks like over watering, I thought this too, but with coco apparently you cant over water. The more you water the more you replace oxygen in the root zone (which by the way is magnificent and very densely packed with ultra white roots!)

Tonight I will pull them all out and put them in the bath tub and flsuh them with like several liters each with 5.8 PH and and EC of 1.6 as someone said they look underfed and I kinda agree with that.

Thankyou all so much for your help

Kronikal_kiwi said:

Also I definitely flushed the coco thoroughly before use. I originally had them bagged in brick coco, and I rinsed that like crazy before use so I got an ec of 0.1 (same as tap water) coming out the bottom. Then when I rebagged them recently I used expanded, pasteurised stuff that didnt need rinsing.

I do evaporate the chlorine out of the tap water. It is cold, like around 15 degrees celcius.

A couple of people are saying it looks like over watering, I thought this too, but with coco apparently you cant over water. The more you water the more you replace oxygen in the root zone (which by the way is magnificent and very densely packed with ultra white roots!)

Tonight I will pull them all out and put them in the bath tub and flsuh them with like several liters each with 5.8 PH and and EC of 1.6 as someone said they look underfed and I kinda agree with that.

Thankyou all so much for your help

Click to expand...

Coco can be overwatered. Stick a brand new clone in a 5 gal pot and you will see what it looks like.
You can't overwater a plant in a proper sized pot of coco. If you flush it with a crazy amount of water you will have other problems, but not exactly what you mean by overwatered.

Kronikal_kiwi said:

Also I definitely flushed the coco thoroughly before use. I originally had them bagged in brick coco, and I rinsed that like crazy before use so I got an ec of 0.1 (same as tap water) coming out the bottom. Then when I rebagged them recently I used expanded, pasteurised stuff that didnt need rinsing.

I do evaporate the chlorine out of the tap water. It is cold, like around 15 degrees celcius.

A couple of people are saying it looks like over watering, I thought this too, but with coco apparently you cant over water. The more you water the more you replace oxygen in the root zone (which by the way is magnificent and very densely packed with ultra white roots!)

Tonight I will pull them all out and put them in the bath tub and flsuh them with like several liters each with 5.8 PH and and EC of 1.6 as someone said they look underfed and I kinda agree with that.

Thankyou all so much for your help

Click to expand...

Not over watering. Just flush plants (2 gallons PHd water for each gallon of pot). Once the PH is straightened out, the lock out will end and plants can feed properly. Yes, they are underfed due to lock out. They will recover fine.

Gidday everyone.

Today I got busy in the room.

I felt that with the plants sitting in the saucers that collected the run off, there was a chance that, due to the nature of coco, this preventing oxygenation. I took all the plants out today, photographed them, and filled the saucers with hydroton so the plants wont be sitting in their own run off.

I flushed each one with PH 5.8 EC 1.6 nutrient and run off was identical.

Link to grow: https://www.icmag.com/ic/showthread.php?t=230303

Thank you all for your help. I reached a point where it said I couldnt give any more Karma today sorry.

I'd raise the lights a little, and stop feeding to runoff. Let the pots dry out a bit between waterings, and add a little cal-mag. As suggested, keep PH right around 6.

Once plants green up, and start drinking heavily, then water daily to runoff.

I worry more about what's going in, trying to grow by reading runoff had me always chasing problems that didn't exist.