Recurring problem with low ph in coco

Whats up everyone, back at it again with low ph in coco. Plants turning yellow from top down. Seems like it always happen once they go into flower. Using 2 gallon smart pots of coco with dyna gro foliage pro and runoff is coming out at 5.3 to 5.5. Plants have been getting fed 1.2 to 1.4 ec. First symptoms are lime green tops that progress to yellow. The rest of the plant looks healthy for most part.

The worst part is that it seems like no matter how much I flush them it just stays there. I have even flushed with plain tap water which mine is very alkaline, but within a couple days the runoff goes back down.


Plants have been babied this time and even just did a complete restart with all new healthy plants. They were doing great until i brought them into flower room. Once they got their first feed with dynagro foliage pro they took a turn downhill. The nutes are a brand new bottle and ive bought so many bottle of this stuff from my grow store that i dont think they have been sitting very long. There are no crystals or anything like that in the nutes. But when test the raw nutes ph it is 1.8.

Really dont know what to do besides change nutes, but my last grow plants were very healthy using same recipe. The 2 grows prior to that i had this exact same problem and flushing does not help. I'm thinking of just running my nutes into tap water because mine is so alkaline that i would think it should be able to break that bond.

Any ideas?

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At what pH and EC are you feeding the plants? pH 5.3-5.5 is way too low.

Even though your water is alkaline, it doesn't have any pH moving power.

Water that is 50 ppm and pH 8 will move the medium pH up much, much less than a nutrient solution that is 800 ppm and has a pH of 8.

I would be very curious what people think of this problem because it has happened to me as well. Hopefully someone can offer some helpful info for the OP and me.

Need to know the pH of nutrient solution in before I can tell you with 100% certainty, but I am 99% sure it's pH = too low = Mg lockout.

My nutes going in are 5.9. This is with ro water and ec of 1.4. Runoff from this is whats coming out at 5.3 to 5.5

low ph issues

low ph issues

Every single time I have low PH issues, light is hitting the hydro.

Even a small amount of light can start the issue. Once its started, even if you cover the rez/pots, the PH issue will continue until hydro is shocked.

Even if you have a cover, it may not be enough. (higher light intensity in flower vs veg can be all the dif)

1) Change hydro.
2) Make better covers.
3) Shock with (food grade) h2o2 or bleach (See Dead Rez posts)

In pinch, lay paper bags over top of your pots (with a slit cut in to accommodate the stem). Hit the natural food stores for h202 (hydrogen peroxide). Not the stuff you buy at the local CVS.


Or you could continue battling the PH issue with daily dose of PH up. Which is so much fun.

All this assumes, the coco mix isn't messed up.. But sense only occuring in flower, guessing that is not the case.

This is in coco and my rez always sits around 5.9 or 6. B

I will bet 100 bux your problem is Mg lockout. This is a classic sign of such.

5.9 is already on the verge of too low, Mg lockout begins around 5.8. This is the biggest myth on the onlin forums, to use such a low pH. It is terrible, terrible advice and leads to this problem in gardens everywhere. I see it time and time again.

If the runoff is as low as you indicate, your nutrients have greatly crashed the medium's pH and you are now in total Mg lockout. The yellow growth is from lack of Mg. Mg is the central ion in the chlorophyll molecule. Without the ability to produce enough chlorophyll, your plants look yellowish instead of green.

The only solution is to raise your medium's pH. I sent you instructions for such in private.

Again, I know this seems counter-intuitive since you see so many people online spouting this as an acceptable pH range; but its really not. It's way too low. The plants can initially tolerate that pH going in because the medium has some ability to buffer the pH before it crashes, but after some time in veg the nutrients stuck in the medium use up all the buffering capacity, and the pH begins to crash. Yours is now WAY low, as evidenced by your runoff measurements.

You need to counteract the low pH and bring it into a suitable range, and then start feeding a higher pH nutrient solution than you are now, once you see improvement. Don't fall back into old habits, they are what is causing your problems now.

if you follow this advice you will start to see the plants green up within 2-5 days. Keeop going in high until you see them green back up, and they will.

You can also foliar feed to help, but it's not a be all end all solution it's really just an adjunct therapy.

Thanks for all that great advice Chimera. I'll definitely put it to use as im about to flush them at 8.8. Will report back in a few days.

Do you have healthy plants in flowering room? Can you bring back some plants in veg room? It is possible to have off gassing issues? Any new equipment?

5.9 is a perfect ph for coco, keep it there. Look through my pics, all grown with 5.9

Ph drop is usually one of two things . Either bacteria/pathogen in the root zone or salt build up...flushing 1x the pots volume with regular strength at 5.9 will fix it if build up. If it's bacteria , I suggest sterilizing the root zone then re innoculating it or running enzymes. I'll guarantee its one of those two. Hope that helps

I have actually read through it twice and picked up a lot of great info. Thanks for all the great stuff in there.

I thought i had some sort of root problem so i restarted the entire grow. Painted the floors and totally sterilized everything and then brought new plants in that were very healthy. They sat happily for 3 weeks in a small tent and once brought into flower room they still looked good for a couple days until i gave them 1st feed of dynagro. Next day leaves were drooping and lime green color was starting. My roots look beautiful right now though so i doubt it could be bacterial infection.

Also dont think it is off gassing because some plants are happy.

What temperature is your rez and root zone? I've seen temps do things like that. I'd foliar spray and flush it with 1/2 strength nutrients with the PH adjusted a lil higher. I use the Advanced Nutrients PH perfect base nutrients and never have ph issues!

With all due respect DJM, that is only ne part of the story, and it ignores the others. Saying that one person successfully uses a pH of 5.9, therefore everyone should do the same, without specifying anything else about your growth parameters (nutrient type, mix ratios, temperature, salinity, moisture content, frequency of feedings, etc, etc, etc) is an idea without any evidence or information needed to accurately correct the problem.

Different nutrient mixes have different abilities to alter pH based on their respective chemical compositions. One nutrient brand may push pH down much further and more quickly than say the brand you are using. Without those two things being equal, you simply can't make an accurate assessment as to whether that is truly the problem.

This pdf sums that all up pretty well should you choose to look it over. http://www.greenhouse.cornell.edu/crops/factsheets/nitrogen_form.pdf

What is known in this case is this:

1) The medium pH is already too low, evidenced by spaceboy's own measurements.
2) Mg is locked out, as per the pictures (and also supported by the pH measurements)
3) Flushing, as you stated, with a single volume of water has failed to correct the problem.


The idea that all growers should do the same as anyone else, without taking into account of the differences in their respective systems (watr source composition, nutrient brand, composition, application rates (concentrations) and frequencies, etc) is problematic.

Surely one can learn by watching what others do, however, every grower needs to be able to read the plants and listen to what the plants are telling them in their garden. Spaceboy is rightly seeing that his plants are crying out for help. You have to be able to use the information from your senses and tools (EC and pH meters) to work along side what you know works for others. When you see it isn't working in your garden, it's better to think it through yourself, rather than blindly follow the methods of someone else.

Using the available information he has provided, it's quite clear that the pH of the medium has crashed, and that this is what is causing his lockout. The solution is not so complex; correct the pH of the medium and bring it into a suitable range, so that the plants may once again pull the required nutrients from the medium, rectifying the nutrient deficiency. Spaceboy should also recognize that his current practices led to the situation he finds himself in, and in the future he should take measures to ensure that this problem does not present itself again. Whether this means watching pH more carefully, using a higher pH to preemptively correct the problem, or switching to a different brand of nutrients with a profile less likely to crash the medium's pH, is something for him to consider moving forward.

I looked over your album briefly, and it is clear that what you are doing works well for you; you have a healthy and productive looking garden. However, it is also clear that spaceboy has a different situation, one that is actually very common amongst indoor growers, and his practices, while inline with yours in terms of pH, are yielding a very different result. This can be corrected using the advice provided. If he follows your advice, I would suspect however that his garden would continue to deteriorate.

I don't claim to be a coco guru of any shape or form, but some problems are the same across many medium types. This is a classic situation of Mg lockout caused by low pH. The corrective action needed is to increase the pH to a suitable range, and once that is accomplished, re-visit his methods to ensure that they are not, once again, causing the problem to re-occur. I personally feel that 5.9 is riding the low edge of ideal, and that a pH of 6.3 is far less likely to yield problems overall.

The one thing that wasn't mentioned spaceboy is to consider again collecting the effluent/runoff, and measure the EC compared to your feeding solution. This will give you a pretty good idea to the level of salt buildup in your coco, which is of course, the other side of the coin related to pH. The more salt in the mix/medium, the lower the pH. If you don't believe me, test the pH of your water before adding food, and then again after adding food. You will see that more nutrients = lower pH.

Hey SB,
Have not used you nutes, but never flush with straight RO water.
Prep your RO prior to adding your base mix or flushing.
I use Canna Coco nutes, ppm of my RO (34) and rain water (6), so prior to any nutes I add GH Cal/Magic to bring the ppm to around 120 (.24 EC). Only then do I add the base nutes and additives. My target vary's depending on stage of growth but will peak at around 750 ppm (1.6 EC), am currently 18 days into 12/12. I will peak next weeks at around 1.8 EC. So that gives me about 1.57 with base nutes minus the beginning .23 EC RO + Cal/Magic and Epsom. I use 1 gram/gallon Epsom.

Now the flush, very important, for one gallon RO, add 1 gram Epsom, 1 gram will raise my ppm by 12 to 13 points, stir and let sit 10 minutes then stir again, measure the ppm/EC the add Cal/Magic to bring the ppm to 120. Let that sit a few hours and then adjust your pH. I use Silica for pH up.

Super Citrus Haze (Sativa dom)

WW (Indica dom)


Both plant LST'ed but the WW I have had to block up to keep up with the stretch of the SCH.

Good luck on getting you stuff in the right place. I hope this helps!

GR

Oh, one more thing, what brand of coco are you using, and do you charge it prior to using it? House and Garden Drip clean is a must,

Please don't flush with 8.8 as this will only create more problems. Flush with like half or 3/4 strength nutes at 6.0 max. Also...the word flush in coco freaks me out. I never flush...never. Even at harvest I feed with 5.8 -6.0 tap water without much runoff to let the plants suck up what's left.

I don't think the fact that the low pH in the root zone is causing the nute lock out is in question here. The question and reoccurring problem according to the OP is what is causing the pH in the root zone to go so low?

MickFoster said:

I don't think the fact that the low pH in the root zone is causing the nute lock out is in question here. The question and reoccurring problem according to the OP is what is causing the pH in the root zone to go so low?

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The problem is everyone's water is different. Chimera put it best.

Chimera said:

At what pH and EC are you feeding the plants? pH 5.3-5.5 is way too low.

Even though your water is alkaline, it doesn't have any pH moving power.

Water that is 50 ppm and pH 8 will move the medium pH up much, much less than a nutrient solution that is 800 ppm and has a pH of 8.

Click to expand...

My water's pH for example drops like a lead weight after touching the nutrients and then again with the coco. To counter it I need to water much higher than the standard 5.8-6.0 pH range given online and let it drift down as water and nutes are used up but eventually even accounting for that drop in pH isn't enough to stop issues and the coco needs a flush to reset it. Everyone's water is different though so the only way to truly know what's going on is to test everything lots of times and record your findings so you can make future grows more predictable.