High pH lockout in coco - tips for reducing

Hi folks,

Experiencing some quite severe lockout issues in coco that seem to be associated with pH being too high.

I know people say that you'll end up having problems if you chase run off pH in coco, but for example I just ran a 5.5pH feed, atleast 20% to waste and the pH is reading at 6.5... Have been trying to correct this issue for some time to no avail, plants looking like absolute death and see a lot of contradicting information on the interwebs.

Firstly, how the hell do I get the pH down - should I keep watering at 5.5ish until it comes down, or I've seen some say that they water with around pH 4 until it gets back into a more acceptable range. And yes I have tried flushing, it seems that my tap water really wants to creep up in pH over time..


Any tips welcome and appreciated

Coco will buffer itself to about 6.5 I would keep feeding at 5.8 and stop worrying about your run off, you're likely doing more harm then good

420Free420 said:

Coco will buffer itself to about 6.5 I would keep feeding at 5.8 and stop worrying about your run off, you're likely doing more harm then good

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Well im not doing any good at the moment. I have been doing that for some time and there has been no improvement, I understand that pH increases from the run off, but by 1 entire pH unit? seems like a shit load

If you have a lock out it probably due to salt build up due to feeding too much or letting the coco dry out.

What ever the cause flush with a low ec solution with a ph of 5.8.

Test your run off ec not ph to determine if you have salt build up.
Test it after flush. Keep flushing until its close to whats going in

As Corey said flush the medium with ph water and watch the EC.

If there’s a build up you’ll notice the PPM spike midway through the flush. Take repeated waterings to get those salts out the media.

coreywebster said:

If you have a lock out it probably due to salt build up due to feeding too much or letting the coco dry out.

What ever the cause flush with a low ec solution with a ph of 5.8.

Test your run off ec not ph to determine if you have salt build up.

Click to expand...

Have been testing EC every single time, been coming out the same as what I'm feeding. Started at a very weak feed (0.6 ec) and saw no improvement, thought they may be using up what was there too quickly .. tried going higher (1.0) ... no improvement

I have been watering daily at 5.8 - 6 for multiple weeks with a new ph meter .. no improvement

coreywebster said:

If you have a lock out it probably due to salt build up due to feeding too much or letting the coco dry out.

What ever the cause flush with a low ec solution with a ph of 5.8.

Test your run off ec not ph to determine if you have salt build up.
Test it after flush. Keep flushing until its close to whats going in

Click to expand...

Is there absolutely no accuracy in measuring coco runoff pH? runoff going up an entire pH unit seems a bit much doesn't it?

Nutty sKunK said:

As Corey said flush the medium with ph water and watch the EC.

If there’s a build up you’ll notice the PPM spike midway through the flush. Take repeated waterings to get those salts out the media.

Click to expand...

This is another thing I always see contradicting information on. flush with plain water or very dilute feed?

This thread might help you out.

Calbrowno said:

Have been testing EC every single time, been coming out the same as what I'm feeding. Started at a very weak feed (0.6 ec) and saw no improvement, thought they may be using up what was there too quickly .. tried going higher (1.0) ... no improvement

I have been watering daily at 5.8 - 6 for multiple weeks with a new ph meter .. no improvement

Click to expand...

How old are your plants?
What deficiency are you seeing?

Did you rinse charge and buffer the coco properly before using it?
I haven’t had this issue yet.. feeding small and large plants with 500-1000ppm with 10-20% runoff

Calbrowno said:

Have been testing EC every single time, been coming out the same as what I'm feeding. Started at a very weak feed (0.6 ec) and saw no improvement, thought they may be using up what was there too quickly .. tried going higher (1.0) ... no improvement

I have been watering daily at 5.8 - 6 for multiple weeks with a new ph meter .. no improvement

Click to expand...

How old are your plants that you were feeding 0.6 ec , 1ec?

What deficiencies are you seeing?

If your feeding too low your ph will rise.

coreywebster said:

How old are your plants that you were feeding 0.6 ec , 1ec?

What deficiencies are you seeing?

If your feeding too low your ph will rise.

Click to expand...

I cant say exactly, they have been in veg for sometime.. they definitely aren't young.

I've got some in wk 2 of flower (yes I know I shouldn't have flipped that's another story) which are showing some signs of recovery, but overall they look like shit really.

Others have been in veg for sometime and definitely grew far too big for their pot so have recently repotted.

coreywebster said:

How old are your plants?
What deficiency are you seeing?

Click to expand...

And I'm seeing a range of symptoms
- very yellow almost white-ish new growth with veins extremely close together, only grow to a small size before wilting up - there seems to be a salt precipitate forming on the leaves
- leaf nodes extremely tight together,
- Older fan leaves have become dark green, some are cupping downward
- new fan leaves are remaining very small, starting at the base of the leaf and following the veins outward, they slowly begin to brown off along the leaf vein itself

Nizza said:

Did you rinse charge and buffer the coco properly before using it?
I haven’t had this issue yet.. feeding small and large plants with 500-1000ppm with 10-20% runoff

Click to expand...

I did not with this particular bunch because I have used the same product in the past without needing to do so, even so I still gave them a good flush once transplanted

Calbrowno said:

I did not with this particular bunch because I have used the same product in the past without needing to do so, even so I still gave them a good flush once transplanted

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I hear alot of people saying high quality coco doesnt need a wash but I think you still need to do a charge and buffering. After watching this video I realized what they are saying about cation exchange sites and how they affect the pH in coco and rob nutrients. If you properly charge your coco you will not run into this problem!

take a few minutes and watch this video try it out! http://www.cannagardening.com/videos/coco_and_buffering
The info you want is at 2:20 in the video. Also realize the quality of coco isn't always consistent. That is why I also wash my coco first always and sift out the fine fibers.
And if you have an extra second, please hit the like button on my post here https://www.rollitup.org/t/mars-hydro-new-giveway-for-ts-1000-with-upgraded-design-already-start-come-on.1021014/page-2#post-15619160

I am trying to win a free light so I can run a side-by-side comparison. HLG vs Mars

Calbrowno said:

And I'm seeing a range of symptoms
- very yellow almost white-ish new growth with veins extremely close together, only grow to a small size before wilting up - there seems to be a salt precipitate forming on the leaves
- leaf nodes extremely tight together,
- Older fan leaves have become dark green, some are cupping downward
- new fan leaves are remaining very small, starting at the base of the leaf and following the veins outward, they slowly begin to brown off along the leaf vein itself

Click to expand...

Sounds like in part and iron or sulphur issue.
But would need to see pics.
I veg with 1.2-1.3ec, just base nutrients, nothing fancy.
Flower with 1.4ec.

What nutrients do you use and what lights?

coreywebster said:

Sounds like in part and iron or sulphur issue.
But would need to see pics.
I veg with 1.2-1.3ec, just base nutrients, nothing fancy.
Flower with 1.4ec.

What nutrients do you use and what lights?

Click to expand...

I use the full nutrifield range - a not so well known brand made in Aus, have used many times with good results.

Vegging under 5 30w led bars, flowering under 600 hps - again used this equipment in the past with good results.

Thats what I thought aswell, and If I understand correctly Iron starts becoming unavailable pretty quick anywhere upward of 6.5pH, which is why I think my lockout issues are due to pH being too high and why Im wanting to bring it down, just a hunch though, I've gone through many different scenarios that could cause this and pH is the only conclusion i come to.

coreywebster said:

Sounds like in part and iron or sulphur issue.
But would need to see pics.
I veg with 1.2-1.3ec, just base nutrients, nothing fancy.
Flower with 1.4ec.

What nutrients do you use and what lights?

Click to expand...

So what do you think I should do? Watering at 5.8-6 is giving me shit results and I'm out of ideas.

Calbrowno said:

I use the full nutrifield range - a not so well known brand made in Aus, have used many times with good results.

Vegging under 5 30w led bars, flowering under 600 hps - again used this equipment in the past with good results.

Thats what I thought aswell, and If I understand correctly Iron starts becoming unavailable pretty quick anywhere upward of 6.5pH, which is why I think my lockout issues are due to pH being too high and why Im wanting to bring it down, just a hunch though, I've gone through many different scenarios that could cause this and pH is the only conclusion i come to.

Click to expand...

Like I said previously if your underfeeding the ph in the medium will rise , does the same with hydro.
Could be a dodgy batch of coco too.

I wouldn't be too concerned with the ph rise myself.

Ignore Run-Off pH
Although it is critical to adjust the pH of the inflow, you should not be concerned with the pH of the run-off water. Your only concern with pH is always providing nutrient solution (inflow) that is in the appropriate range. Many growers make the bad decision to provide nutrient solution that is outside of the acceptable range in a misguided attempt to correct run-off pH values. This can destabilize the pH of the nutrient solution in the root zone and make nutrients unavailable. To avoid this common pitfall, simply ignore the pH of the run-off.

As far as im aware there is no nutrient issue in coco that cant be corrected with a flush as long as your nutrients are balanced.