PH or CalMag issue?

[BigD1128]

Problem: leaves are beginning to show pale green/ yellow spots.

Medium/grow method: Coco

Feed: and supplements used: First 20 days I was using Megacrop. I switched to GH Cocoteck grow since issues began.

water source: distilled water

Strain/age: Sour Crinkle 22 days old

light used: 2 Citizen COB LED from Timber growlights. 38” above canopy running at 75-80% spaced 12” apart on center

Climate: climate has been consistent. Temp is constantly 73-77’ F RH is 45-55% I don’t have an exhaust fan connected yet but I do have a 6” round fan on low speed blowing over the plants.

Additional info: This issue began a few days ago. I was using megacrop @300ppm ph5.8-6.0 since the issue began I switched back to Cocotek. I am more familiar with this brand and it is designed to be used in Coco. For 3 days now I have been using distilled water, adding 200ppm CalMag then adding Cocotek grow A+B to get 475ppm. My camera doesn’t show the yellow spots as much as they look in person. If I look close it seems as the new growth has some spots as well.

 

[Troy01]

Sounds like you are doing the right thing. PH is perfect for CoCo and addition of Cal Mag will certainly help fix the problem. Have you calibrated your PH pen lately? I checked mine out and it was a good .5 points off. I have since upgraded my pen.

I'm growing in pure CoCo under a combination of COB's and LED. I'm using PH Perfect product in regular tap water and only occasionally check the PH. So far I'm not having any problems.

Not sure what your tap water is like but if on the hard side it might add the calcium needed.

 

[BigD1128]

@Troy01 yes my ph pen has recently been calibrated as well as brand new batteries. To be honest I am in a new place and I haven’t really checked my tap water. In the past I could never keep my feed ph stable using tap water so I haven’t tried here. I will look into ph perfect nutes though. Balancing ph is such a pain.

 

[Yeatster]

Appears to be Mag deficiency to me. I would give epsom salt @ 1/4 tsp/ Liter in addition to Calmag. That's my opinion, there are many others better than I

 

[Troy01]

I've not used Epson salt myself in weed. It makes sense and back in my day of breeding Orchids I use to use it to initiate blooming. It's definitely a inexpensive source of Magnesium.

I was looking last night and the Advanced Nutrients Connoisseur CoCo (PH Perfect) that I'm using and noticed that it already had both Calcium and Magnesium in it. I have been supplementing with additional Cal-Mag and so far haven't had a Cal-Mag issue.

 

[BigD1128]

THis is also my first run with true COB lighting. I notice the yellowing is on the largest upper leaves and not so much on lowers. Is it possible this could be the begging of bleaching?

 

[MickJ]

THis is also my first run with true COB lighting. I notice the yellowing is on the largest upper leaves and not so much on lowers. Is it possible this could be the begging of bleaching?

Looks like calmag to me too


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[Troy01]

THis is also my first run with true COB lighting. I notice the yellowing is on the largest upper leaves and not so much on lowers. Is it possible this could be the begging of bleaching?

How close is your COB?

Recommend you do the hand test. Hold your hand under the COB at the same distance as your plant for 30 seconds. Are you feeling heat on the hot side. If so you are too close.

I have my COB at 12" over my plant and not having any heat or bleaching.

 

[BigD1128]

@lunarman here ya go

 

[lunarman]

@lunarman here ya go

thank u man. i reloaded my res today with full calmag. i had reduced cal mag since sprout. could be the fix.

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