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

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!

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

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

What stage are ya plants at

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 said:

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

Click to expand...

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

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

Trickyticky said:

What stage are ya plants at

Click to expand...

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.

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

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.

macsnax said:

Is there a reason you're checking runoff?

Click to expand...

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

Trickyticky said:

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

Click to expand...

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.

BorgCube said:

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/

Click to expand...

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.

macsnax said:

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

Click to expand...

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...

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...

Macncheesehaze said:

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.

Click to expand...

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.

BorgCube said:

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...

Click to expand...

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

macsnax said:

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.

Click to expand...

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.

BorgCube said:

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.

Click to expand...

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

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

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