OMGā¦YEAH, someone understands!! EXACTLY!!!
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early flower @ 1/3/2ā¦,mid flower @ 1/3/3ā¦late flower at 1/2/5 or so
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Your method sounds good to me, but I wonder if i might be good to test your water all by itself for PH drift?
I suspect the alkalinity/c02 drift thing will vary - maybe a lot - from one location to another and possibly also with the seasons or depending on rain, treatment from a city, re-charging water softeners, etc etc.
Im not sure how we can narrow that down for people. They are just going to have to do some testing on their water to see how it reacts.
IIRC, when I did my tests, RO water was very slightly more stable than my tap water - maybe - but not enough to make a real difference. Plus, my tap water changes depending on the season or how much rain we have had - Im on a well.
It still seems a little odd that the Jacks had so much drift when the Mega Crop didnt. Were they both started/tested at the same initial and final temps? Same time for the RO water to equalize with the atmosphere?
I dont actually expect to see all that much change just from the alkalinity - at least not based on the level of aeration you were using - which was basically just gentle stirring? I wonder of the Jacks was still dissolving maybe? It took forever for it to dissolve for me.
Im ramblingā¦
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I canāt. Or I should say, donāt want to risk the probe. It pure RO water with exceedingly low EC (unmeasurable with conventional probes). Iām afraid an extended drift test would quickly leach the probe to itās death. Intermittent spot checks puts it near where one would expect it, ~PH7.
To me, this effect looks to be inherent in the formulation of 321. Follow-up evaluation of the same source of water using a different formulations has not shown such dramatic drift.
With that said, it doesnāt rule out something went amiss with this particular test and, as such, Iāll be taking another look see. Iām considering two possibilities, a) the stored RO water intermittently contained high levels of dissolved CO2, b) carbonates are included in the 321, c) some combination of the two.
edit: Also possible that the probe needed re-hydration, it was sitting in storage solution for an extended period of time. Letās see what the follow-up test says. So, d) probe hydration problem
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Re-running the tests on the 321 and Iām not seeing the initial drift any longer.
It was probably d, āprobe hydration problemā or a bubble in the probe.
So here is the revised information.
The components were prepared for 1 gallon using:
- 3.685g Part A (5-12-26)
- 2.438g Part B (15-0-0, Calcium Nitrate Hexahydrate)
- 1.134g Epsom Salts (Magnesium Sulfate)
500ml was adjusted by dilution to the target 1.7EC. The solution is clear up until around a PH of 7.5 after which it starts to turn cloudy. You can see the slope change slightly as precipitation occurs.
Drift, terminated measurement early due to minimal noticed drift:
Buffering comparison against MC:
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Sorry for the slow replies - Im still not at 100%.
If anything, the Mega Crop actually looks even better on this plot than it did before as far as the flatness of the curve and the relative slope compared to Jacks.
Could you zoom in on the area between say 5.0 and 6.5 or so? Thats the region most of us are primarily interested in.
In this test, Mega Crop show stronger buffering action than Jacks, and yet, a significant number of people experience just the opposite in their grows.
I cant think of anything - other than bacterial growth - that could account for the PH swings people see with Mega Crop that dont show up with Jacks.
If it was just the alkalinity in someones water, then that would effect Jacks and Mega Crop the same way.
To be fair - its NOT just Mega Crop that has this issue. Ive seen it with Advanced Nutes and Fox Farm nutes. All three of those have organic components. It seems to me it has to be those organics that are the cause. Bacteria, algae, etc eat that stuff and drive the PH up as a result.
I was just reading an article about growing algae in tanks to sequester/trap carbon. They pointed out that as algae eat, they use up carbon dioxide, and convert it into some form of plant matter. That action will drive PH up for sure.
Its the same cycle that occurs with the alkalinity thing - remove C02 (via aeration) and the PH goes up.
One big take away for me is that it looks like organics and hydro just dont mix.
It also makes me wonder about folks using ābeneficial bacteriaā to keep root rot down. Seems to me they are just adding another layer of problems on with PH control.
I think this is a very very important find. Thank you for doing this @Northern_Loki !!!
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Linear regressions are based on least squared calculation between ~5.6 to ~<6.5 PH.
Thereās a bunch of things that could differ Iād think:
- ratio of ammonium form of nitrogen (in-situ, plant ion-exchange)
- CCE, carbonates / bicarbonates / carbonate cycle
- inherent buffers in nutrient formulation. monopotassium phosphate, for instance. e.g. buffers we get for free.
- organics, biological effect
- buffering amendments
- precipitation
Organics seem to be a likely culprit for several of the experiences shared across the various threads. I think maybe alkalinity in a couple of other examples (e.g. keeps drifting to ~6.3). And, Iād assume precipitation could also be causing PH shift in some scenarios.
The ammonium ratios will effect the natural PH shift due to plant feeding. Having slightly higher ammonium ratio can have a buffering effect but, unless well planned, it might be akin to skating on the razor of toxicity.
Buffer amendments along with inherent buffers have been discussed in this thread.
Which organics are feeding micro-organisms would be one question. Is it amino-acid based chelates? Or something else in thereā¦
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This is fascinating. Thank you for taking the time to do this, and reporting the results in such a clear manner. Much appreciated!
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Just saw this part. Thatās a good question.
Is there a difference? Iād think weād be talking aerobic vs anaerobic. Aerobic typically considered fine? PH effect of aerobic bacteria? I donāt really know. Should research this.
There are certainly some aerobic bacteria that can have a profound effect on pH just for example, but the ones Iām familiar with are not likely the ones weāre concerned about here.
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From my reading about pool algae, there are dozens of varieties - just for starters, there are green and red and orange and brown types.
In my various rez setups over the last few grows, Ive had brown, and green for sure. Actually, two different types of green - long threads and the thin film type. Plus Iāve had just plan slime - clear and brownish, and cloudy water with and without smells. Plus, Ive had regular old root rot.
As far as I can tell, every type Ive had causes the PH to go UP. I would assume all the ones I had were aerobic, just because I have been doing crazy aeration on all my rezās - but I cant be sure about that.
Without a lot of lab testing, I dont know how we could be sure. Bottom line is - and what matters to us - what does it do to the PH?
In my case, I am very curious, but it doesnt really matter what exact kind of algae/bacteria are driving my PH up when I use organic containing nutes. There isnt one single thing I can think of to stop them unless I move to a dry state where it never rains, or give up on hydro and go soil only. Ive tried chlorine in hi doses, copper in hi doses and nothing works. When I put in enough chemicals to kill the bacteria, it damages the roots. Actually, it doesnt kill the bacteria, and the roots still die.
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Test: fun spreadsheet with MC 1 and 2 part.
https://bit.ly/2Wpespd
(If link not working hmu)
Thisā¦
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Found the NASA paper discussed earlier regarding MES and ion exchange resins, author just happened to be B. Bugbee, how about that:
bugbee1985.pdf (571.0 KB)
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gravity rainfall system with pre-mesch filter in front of the pump and di filter with ion exchange resin behind the pump
mega crop fertilizer + bud explosion, cal mag in the spray every week
what resin to use for mega crop v2
What we had utilized here, to compare buffering to an ion exchange resin, was Amberlite CG-50. That variant is a relatively fine powder. There are likely other exchange resins that have similar properties that are not quite as fine but if your in-line filter has a fine enough mesh it would probably work fine.
Be aware that ion exchange resins can be tricky as they absorb and release ions to maintain a PH. And, what they absorb and release will vary depending on the resin type and how they are pre-conditioned (they typically should be conditioned first). For instance, some resins could absorb specific ions that you really donāt want it to absorb. Preconditioning can help such scenarios. Read the Nasa paper above to get a feel for some of the issues they had encountered while noting that it is an old paper utilizing only a single specific type of resin.
Here is the description for Amberlite CG-50:
General description
Amberlite CG50 is a weakly acidic, carboxylic acid type of cation exchange resin.
Application
Weakly acidic cation exchange resin useful for isolation and purification of cytochrome C, amines, drugs, metal ions, thrombin, and neutralization of solutions. Meets requirements of FDA Food Additive Regulation 21 CFR 173.25.
Amberlite CG50 has been used as a reference cation exchange resin for the examination of binding and elution of genotoxic aminopyridine impurities from pharmaceuticals on molecularly imprinted polymers (MIPs). It may be used for the purification of bovine lactoperoxidase prior to the investigation of inhibitory effect of propofol on lactoperoxidase.
Also, see the following regarding the Torus PHPerfect which uses ion exchange resins ā¦ but I do not know what type:
Also see:
Also, you may want to consider how this would work to your schedule. If youāre swapping the nutrient solution on a regular basis, you may not really need to overly buffer the solution. Or, you may want to consider formulating the nutrient solution to include a small amount of MES to slow any PH drift.
My opinion is to trial run your system to watch the PH behavior to understand the PH range, direction, and speed ā¦ then consider a buffering or ion exchange resin solution. If you feel this system is susceptible to infection, this probably can be evaluated prior to adding any plants into the system.
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