K-Lite has been around a few years now... updates?

Slippertalk Orchid Forum

Help Support Slippertalk Orchid Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Do you know how to correctly measure the pH of samples of such low ionic strength using an electrode-based instrument? Enlighten the rest of ST so they can accurately measure their rainwater.

Why not address the fact that I have shown you several links to papers that measured rainwater samples at pH 7 and above. You said it was impossible for rainwater to be pH7, it's not impossible.
 
Do you know how to correctly measure the pH of samples of such low ionic strength using an electrode-based instrument? Enlighten the rest of ST so they can accurately measure their rainwater.

Chris, if you don't mind, can you share how to do it? From my experience, I know that pH values of purer water (e.g. milli-Q water) doesn't stabilize with most electrodes (normal molecular biology lab grade equipment, which can handle Tris buffer, nothing special). But some other electrode seems to stabilize with purer water. I kind of understand why it is difficult, but I'm weak in chemistry, and I have been wondering about it for a while. Are there particular types of electrodes better for this type of application?
 
Why ask about CO2?
I said "There are no atmospheric pollutants from manufacturing, the air is as clean as can be, and it is brand new unused air."
I hope you are not going to say that CO2 is an atmospheric pollutant.

Of course it is. The point is not up for discussion or debate. Not to mention, I'd love to see an atmospheric chemistry/air quality for where you are in Peru. Because, frankly, you're fond of proudly spouting complete, utter bullshit. I'm just here to make sure people don't interpret it as expertise in any form of atmospheric chemistry.
 
Chris, if you don't mind, can you share how to do it? From my experience, I know that pH values of purer water (e.g. milli-Q water) doesn't stabilize with most electrodes (normal molecular biology lab grade equipment, which can handle Tris buffer, nothing special). But some other electrode seems to stabilize with purer water. I kind of understand why it is difficult, but I'm weak in chemistry, and I have been wondering about it for a while. Are there particular types of electrodes better for this type of application?

Naoki,

There are electrodes specifically designed for low conductivity solutions.

There are many things to consider. First, typical electrode storage solutions act to contaminate the boundary layer of the electrode and even small amounts can completely contaminate low ionic strength sample solutions so badly that a measured pH value is meaningless. Second, low ionic strength solutions are extremely susceptible producing static charges that will generate electrical mimicry of H+ ions, and many lower quality pH units are not sufficiently shielded and grounded to eliminate this in a low ionic strength solution. Third, junction potentials will often form because of unequal kinetics of migration of the charges involved (H+ and usually Na+), meaning sometimes minutes or hours are required for a stable reading.

Electrodes suited for pure applications have a continuous leaking fills solution to prevent a junction potential (Most modern pH electrodes are a sealed bulb design with a reference electrode solution existing as a gel coating, hence their long lifespan. Leaking electrode fill solutions obviously need to be frequently refilled). Other methods involve a full suite of calibrations using low ionic strength buffers and storage solutions.

It is typically possible to get a close, stable reading using extremely high purity KCl to make the sample have a similar ionic strength as the filling solution of a typical electrode and achieve stable (easy to try!). For example, 18.2 megaohm/cm water typical of milli-Q systems, if sealed from atmospheric gases, DOES have a pH of 7.0 at 25°C. Typically, bumping the conductivity of the sample solution to 2 mS/cm is sufficient to get a fast, stable response.
 
Last edited:
Of course it is. The point is not up for discussion or debate. Not to mention, I'd love to see an atmospheric chemistry/air quality for where you are in Peru. Because, frankly, you're fond of proudly spouting complete, utter bullshit. I'm just here to make sure people don't interpret it as expertise in any form of atmospheric chemistry.

Wow!
Are you being a sore looser?
You are rude. Why?

I never presented anything I said as atmospheric chemistry. I simply said and showed what my pH meter read, nothing more. I'm not representing anything as science only what I personally see and experience.
 
Last edited:
The global average CO2 content is now around 400 ppm. You can see that it takes far less than that to greatly push the pH off neutral.

H20-CO2-pH.gif
 
Who's side are you on now? :poke:

Here.... This research address neutral rain.

http://www.scielo.org.mx/scielo.php?pid=S0187-62362014000100004&script=sci_arttext

It happens. My observation was seeing it happen on the day I took the samples.
I'm not on one side, I despair to see a sane respectful and global talk about k-lite and relevant issues around. (not saying you're not respectful)

Rain just can't be neutral, and from the Vascular Epiphytes book, is more a bit all over the place, for reasons that are sometimes far from Amazonia or just because the CO2 level are on Earth what they are today. There's no such thing as "pure" water falling down there (or anywhere). Not by evil chemist standards, nor by orchidophile standard. :evil:
 
Try to keep up. No one is talking about pure water. We are talking about the pH of rainwater.
Chris, when you'll stop overinterpreting what people post it'll be a nice move. Your input is always interesting, but your constant attacks on sometimes shortcuts or misreads is tiring. I was especially pointing out that rainwater CAN'T be "pure", and moreover in the Amazonian ecosystem. As I said, I'm not on one side, I ponder inputs usually in popcorn mode as there's nothing else to do under the missiles flying.

Due to my current state of health :eek: I will not interfer more in the subject, I have better to do with my energy left. I just hope we'll be all able to have a sane, informative and respectful thread one day on k-lite and global issues around it (like water, the way orchids bathe their feet, the soap used…) and especially at finding why it does marvels to some and leads to disasters to others (as there was in another thread and it was interesting). It'll be a nice move.

I'm out, don't answer please, I'm too tired and I'm not into the heart of the talk anyway, thank you. :ninja:
 
After all is said and done, I must mention that for my Paphs I would continue to use the K-lite. I will observe for problems. So don't want to rule this fertilizer out entirely. Just some things work and some things don't work for each individual growing needs.
 
Addressing a much earlier series of comments:

Over the last couple of weeks, I had conversations with three university horticulture professors and two plant-nutrient specialists in that industry, and they independently and unanimously stated that general yellowing of leaves ("Of course it will be older ones first") is very likely a simple insufficiency of nitrogen, and not likely due to other nutrient shortages.
 
Addressing a much earlier series of comments:

Over the last couple of weeks, I had conversations with three university horticulture professors and two plant-nutrient specialists in that industry, and they independently and unanimously stated that general yellowing of leaves ("Of course it will be older ones first") is very likely a simple insufficiency of nitrogen, and not likely due to other nutrient shortages.

Perhaps there is not an insufficiency of nitrogen but just the wrong type (
i.e. too much nitrate and not enough ammonium and urea.)
 
We all consider nitrogen as a single species. But there are multiple forms of nitrogen that have very different chemical and biological properties.

Ammonia (or ammonium ion if you prefer) is used more directly by plants, but it is a strong cation, and actually antagonizes / competes with other cations K, Ca, Mg.

Nitrate is not used directly in plant protein synthesis until after it gets converted from nitrate to ammonia by the nitrate reductase system (which requires ATP expenditure i.e phosphate use). Also nitrate is an anion which antagonizes / competes with other common anions such as sulfate, chloride, bicarbonate, and phosphate. If K lite is used in strict RO settings the above anions are going to be in short supply relative to the high nitrate concentration.

In real world solutions (such as the interstitial water around plant roots). There's very little nitrogen of any kind while Ca, Mg, (cations) sulfate, and chloride abound.

So I've been considering the other half of antagonistic interactions - anionic interactions (primarily between nitrate and sulfate phosphate), and found that if I boost phosphate and sulfate I can increase "greenness" without changing N input. In this case the cation attached to the anions is Mg, which we all commonly associate Epsom salt (MgSO4) addition with boosting "greenness" already. But in order to increase phosphate I neutralized phosphoric acid with MgOH.


But overall getting to eco-relevant concentrations of ions is the path that's working for me.
 

Latest posts

Back
Top