Veins yellowing, runoff PH suddenly quite low (5.2) with a high EC of 2.0, plant is close to harvest

[BorgCube]

Grow is in coco coir, using the AN line of nutrients. Feed water was always measured at 1.0-1.1 EC, pH set to 5.7-5.8. Runoff has typically been good, but it seems to have taken a very fast turn for the worse. I've checked my instruments, and they are well calibrated.

Is this typical close to harvest? I worry that flushing now would do more harm than good - so I wanted to check with some pros to get some advice.

My instinct is to prep some pH'ed calmag water (which gives an EC of 0.8 ) and just flush until the RO EC reaches 1.1-1.2, but I'm not sure how hard I should chase run-off targets.

Attached a pic of a damaged leaf, and a close up of trichomes.

Thoughts? Thank you!

 

[Trickyticky]

Try running ya ph higher, round the 6.1-6.2 mark better uptake at your stage of flower

 

[Macncheesehaze]

Weird I literally had the same thing happen. Went from 5.8 to 5.2.

 

[Trickyticky]

What stage are ya plants at

 

[macsnax]

Is there a reason you're checking runoff? More often than not it can send you chasing your tail. If the plants are happy and looking good, there's no need to worry about it. I agree with the above post about running a higher pH too. I run 6.3 from veg through flower in coco, couldn't tell you the last time I checked runoff pH or ppm.

 

[Trickyticky]

Try running ya ph higher, round the 6.1-6.2 mark better uptake at your stage of flower

Ah sorry forgot . Ya might also want to drop ya EC to 1.4 or there abouts, lower if havnt got that long left ,
Every thing I say is my opinion,
Ya can take it or leave it .
Happy days

 

[Trickyticky]

Yeh . Like macsnax says don't bother chasing run off unless your plants have issues . Just keep a check of what ya putting in , and at what quantities. Not too much too soon

 

[Macncheesehaze]

What stage are ya plants at

Mine are at exactly 2 weeks of flowering today. Everything looks good. All I did was adjust. I only checked mine because my autopot got knocked and leaked all over so I dumped it into a bucket and said screw it maybe I can dump it back in the Rez so I checked it and sure enough 5.2 so I just replaced the whole Rez.

 

[Trickyticky]

If it was me a would be checking ph and ec on a daily basis as they can both fluctuate , but yeh 6.2 or there abouts

 

[BorgCube]

Ok thanks. The yellowing veins seemed like lockout issues to me, which makes sense if you consider the pH of 5.0 (near everything is locked out at that level). So I was wondering if I should FloraKleen it to a more nominal range; am assuming that salt build-up is throwing pH and EC. I always water to 20% runoff.

Is there a reason you're checking runoff?

Yes, I've been following the guides on cocoforcannabis.com, checking RO periodically is recommended: https://www.cocoforcannabis.com/managerunoffec/

 

[Macncheesehaze]

If it was me a would be checking ph and ec on a daily basis as they can both fluctuate , but yeh 6.2 or there abouts

What makes ph fluctuate? All I do is mix my Rez and throw it in. No air pumps nothing. What’s causing it to change? I’m running roots organic spikes hydroponic mix with canna coco a and b and jacks professional cal mag. I ph to 5.8. (I’ll raise to 6.2 if that’s better) and atleast 2 times my ph has changed with nothing happening to it. I don’t get how it’s dropping.

 

[macsnax]

Ok thanks. The yellowing veins seemed like lockout issues to me, which makes sense if you consider the pH of 5.0 (near everything is locked out at that level). So I was wondering if I should FloraKleen it to a more nominal range; am assuming that salt build-up is throwing pH and EC. I always water to 20% runoff.



Yes, I've been following the guides on cocoforcannabis.com, checking RO periodically is recommended: https://www.cocoforcannabis.com/managerunoffec/

Just went back and looked at your pics. That is early Mg deficiency. Running coco, r/o water, LED's, all cause a higher consumption/need for Mg.

 

[BorgCube]

That is early Mg deficiency. Running coco, r/o water, LED's, all cause a higher consumption/need for Mg.

Yeah I thought so too, but I've been giving 2ml/L of Sensi-Cal CalMag with every feeding. Could it be natural senescence? Plant is probably 1 week away from having the right amount of amber for harvest...

 

[BorgCube]

Or, simply locked out because of salt build up and bad pH I suppose. There'll be no Mg absorbed at that level of acidity...

 

[macsnax]

What makes ph fluctuate? All I do is mix my Rez and throw it in. No air pumps nothing. What’s causing it to change? I’m running roots organic spikes hydroponic mix with canna coco a and b and jacks professional cal mag. I ph to 5.8. (I’ll raise to 6.2 if that’s better) and atleast 2 times my ph has changed with nothing happening to it. I don’t get how it’s dropping.

It's likely your water source or nutes causing the fluctuation. If you can wait a few hours or overnight after mixing a new batch before pH-ing it can help. More often that not it's those two things causing pH to drift. I switched to the floraflex dry nutes line a while back to get away from the fluctuations. R/O water and the floraflex line have things pretty stable, been loving it.

 

[macsnax]

Yeah I thought so too, but I've been giving 2ml/L of Sensi-Cal CalMag with every feeding. Could it be natural senescence? Plant is probably 1 week away from having the right amount of amber for harvest...

At that stage I wouldn't worry about it. Let it fade out bro

 

[BorgCube]

I switched to the floraflex dry nutes line a while back to get away from the fluctuations. R/O water and the floraflex line have things pretty stable, been loving it.

Interesting, I'll give those a go in the future. Am currently using the Advanced Nutrients line. Grow/Micro/Bloom, and the supplements at different phases (Piranha, B-52, Bud Candy, Overdrive). Seems to have worked well to date, but something really hit the fan in the past week.

 

[macsnax]

Interesting, I'll give those a go in the future. Am currently using the Advanced Nutrients line. Grow/Micro/Bloom, and the supplements at different phases (Piranha, B-52, Bud Candy, Overdrive). Seems to have worked well to date, but something really hit the fan in the past week.

What is your water source? I want to say anything over 1-150ppm base is going to cause fluctuations.

 

[Trickyticky]

Yeh he been running 5.7- 5.8 so plants won't uptake mag as easy as it would if ph was at 6.2 ish

 

[myke]

iME letting a pot dry just a little too much will cause the ph to drop.