Is Phing Flush Actually Even Possible?

[Dirtbag]

Haha, I've got to add something here. The content of the OP went over my damn head.

I didnt get the bit where he is adding ph down and seeing it rise back up again within minutes....In my reply I didnt mean you cant "adjust" the ph of RO, just that you cant reliably "test" the ph of RO.... good grief. I can see how my reply seemed confusing lol

I agree with some other who said ditch the hanna. Adding ph down will absolutely drop the ph and keep it down, it shouldn't ever drift back up that high naturally. So either your ph down consists of a volatile gas or your meter is playing tricks on you.

I've had the same Bluelab ph pen for I think 3-4 years now? highly recommended. Store it in KCL or ph4 buffer.

 

[Ikkt]

The difference is we’re using what are likely
very cheap meters compared to your lab quality ones. The manuals of ph meters aimed at dope growers give u no directions for restoring your probe, they just want u to buy a replacement. What’s even more confusing is the difference between what manufacturers recommend for their equipment. Hanna says to never touch the actual probe doing so could ruin it. Bluelab sells a cleaning kit that includes a tooth brush to scrub the probe. Hanna says to store the probe in KCl, bluelab says u can store it in ph4 solution. It’s a little confusing. Over time I notice the probes take a little longer to give a stable reading but eventually give the correct readout. The new probes react instantly. What’s one of your lab grade units cost?

They aren't that expensive. I got the most basic unit, I think they're about 80-100€/$ for the whole pH meter todax. A replacement electrode is nearly as much, I think 50-75 depending if it's a gel- or liquid electrolyte electrode. The Electronics are very simple so the box doesn't add much to the price.
Nice thing is you can also take permanent readings with the liquid electrode, you only have to open the refill hole of the electrode and attach a 9V adapter.
Btw. a friend had a Hanna meter and it lasted for ~5 years ('till he broke the glass...) with a couple of cleanings iirc.
When the reading gets inconsistent it doesn't mean the probes gone bad, it's most likely a dirty diaphragm and cleaning can take care of that. Several times actually, as long as you only measure mild solutions as we do!

I would have thought the cheaper meters just copy lab equipment manuals. In the end all of these pH meters work the same.
I'd do it like Greisinger says:
For gel electrodes:
https://www.greisinger.de/files/upload/en/produkte/bda/GPH114_EN.pdf
For liquid electrolyte electrodes:
https://www.greisinger.de/files/upload/en/produkte/bda/GPH014_e.pdf

(Just saw that the EN Manuals are a little different, they advice to just use window/Glas cleaning stuff for "regular" dirt. I'll try it next time my meter won't stay steady. So before you throw a electrode away just put it in some windex or whatever and give it a try.
Btw. you can carefully rub the diaphragm with a paper towel if need be, just never touch the "bulb"!)

And I think pH4 buffer is just (colored) 3mol KCl, that's why it doesn't matter. That's why you always calibrate the meter with it first to its internal reference electrolyte and choose the second calibration point depending on desired pH range and calibrate it second. Not absolutely sure though.

 

[Ikkt]

Haha, I've got to add something here. The content of the OP went over my damn head.

I didnt get the bit where he is adding ph down and seeing it rise back up again within minutes....In my reply I didnt mean you cant "adjust" the ph of RO, just that you cant reliably "test" the ph of RO.... good grief. I can see how my reply seemed confusing lol

I agree with some other who said ditch the hanna. Adding ph down will absolutely drop the ph and keep it down, it shouldn't ever drift back up that high naturally. So either your ph down consists of a volatile gas or your meter is playing tricks on you.

I've had the same Bluelab ph pen for I think 3-4 years now? highly recommended. Store it in KCL or ph4 buffer.

As far as I know it's the CO2 gassing out, eliminating the carbonic acid and letting the pH drift back up. The carbonic acid is quite an important factor considering pH of aqueous solutions, but I don't remember the details exactly.
I think it's something like this:
Car.acid and hydrogen carbonate are in an equilibrium. When you add acid you shift it to the side of carbonic acid. That alters the pH reading. CO2 gasses out so you got less car.acid which alters the pH reading to a higher pH.
Would have to sit down with a piece of paper to get it together for shure though.
Iirc the carbonic acid has more impact on pH reading than the added acid by itself.

You also have to consider that certain gasses can permeate the osmosis membrane and get concentrated in the permeate. So a shift in pH in fresh RO water (which isn't RO anymore and behaves as such when you add an acid or anything) is to be expected I think.
There are special electrodes for very low ppm solutions, they're able to measure RO water correctly. They're standard in certain labs but need constant calibration I've been told.


(Anyone: Why is my other reply "awaiting approval"? Cause there's a link in it?)

 

[PharmHand]

They aren't that expensive. I got the most basic unit, I think they're about 80-100€/$ for the whole pH meter todax. A replacement electrode is nearly as much, I think 50-75 depending if it's a gel- or liquid electrolyte electrode. The Electronics are very simple so the box doesn't add much to the price.
Nice thing is you can also take permanent readings with the liquid electrode, you only have to open the refill hole of the electrode and attach a 9V adapter.
Btw. a friend had a Hanna meter and it lasted for ~5 years ('till he broke the glass...) with a couple of cleanings iirc.
When the reading gets inconsistent it doesn't mean the probes gone bad, it's most likely a dirty diaphragm and cleaning can take care of that. Several times actually, as long as you only measure mild solutions as we do!

I would have thought the cheaper meters just copy lab equipment manuals. In the end all of these pH meters work the same.
I'd do it like Greisinger says:
For gel electrodes:
https://www.greisinger.de/files/upload/en/produkte/bda/GPH114_EN.pdf
For liquid electrolyte electrodes:
https://www.greisinger.de/files/upload/en/produkte/bda/GPH014_e.pdf

(Just saw that the EN Manuals are a little different, they advice to just use window/Glas cleaning stuff for "regular" dirt. I'll try it next time my meter won't stay steady. So before you throw a electrode away just put it in some windex or whatever and give it a try.
Btw. you can carefully rub the diaphragm with a paper towel if need be, just never touch the "bulb"!)

And I think pH4 buffer is just (colored) 3mol KCl, that's why it doesn't matter. That's why you always calibrate the meter with it first to its internal reference electrolyte and choose the second calibration point depending on desired pH range and calibrate it second. Not absolutely sure though.

Very nice replies, thank you sir. Learned ALOT of stuff that would have taken me a lot of digging and searching- awesome. I’ll most definitely try the pepsin enzymes and windex. I’ve got at least a few old probes I’ll clean up and compare against the new ones and let y’all know the results.

And fwiw I really like the Hanna units. I remember a time when the only options available to dope growers in the Vancouver bc area were Hanna and those super basic Milwaukee ones that aren’t even waterproof. I always had good luck w the Hanna’s they are high quality units. I had one that read to the second decimal point that I used for 4-5 years until I accidentally smashed the bulb. Held its calibration nicely too.

And that bit about the carbonic acid accumulating and dissipating matches my observations perfectly.... So informative.
Thanks boss

 

[Dirtbag]

Ph wont swing back up that high because of off gassing carbonic acid. The off gassing via surface agitation can take up to 24 hrs and (normally) only results in ph drift of a few points, like 0.3-0.5 max. You would never see an almost instantaneous neutralization of a ph down adjustment from offgassing. Though I have seen some wild swings with "mixed nutrients" being aerated. The ph can really swing with so.e nutrients as volatile acids in the solution are off gassed. But that's not a phenomenon you see with rO.

As for storage solution, it's actually got a much higher concentration of KCL than ph 4, test them with an EC meter and you'll see. The storage solution is much more in line with the concentration of KCL in the probe itself, which reduces osmotic pressure and prevents KCL being drawn from the bulb, which over time, causes the proble to read slow.

 

[Ikkt]

I'm not sure about the CO2 as I saw quite big pH fluctuations in aquariums with heavy CO2 supplementation when there was too much agitation. And ro water could have a lot of CO2, but I would have to read up on gas permeability in ro membranes and am definitely too lazy today. You could very well be right though and it's just the meter having problems with the low ppm solution.

Good to know about pH4/KCl. My Storage solution is empty and I thought of putting it in buffer but will mix a new bottle then. Didn't think of testing the ec.
But now that I think of it it's quite obvious. KCl doesn't give consistent readings, especially nowhere near 4.
Btw. if the probe goes slow change the reference electrolyte if possible. I change it every time I clean the probe.

 

[Dirtbag]

I'm not sure about the CO2 as I saw quite big pH fluctuations in aquariums with heavy CO2 supplementation when there was too much agitation. And ro water could have a lot of CO2, but I would have to read up on gas permeability in ro membranes and am definitely too lazy today. You could very well be right though and it's just the meter having problems with the low ppm solution.

Good to know about pH4/KCl. My Storage solution is empty and I thought of putting it in buffer but will mix a new bottle then. Didn't think of testing the ec.
But now that I think of it it's quite obvious. KCl doesn't give consistent readings, especially nowhere near 4.
Btw. if the probe goes slow change the reference electrolyte if possible. I change it every time I clean the probe.

Good tip about replacing the reference electrode. Unfortunately that is something I cant do with my bluelab, not that I've needed to. It still reads as fast as the day I got it several years ago. Though I'm very careful to always store it in fresh solution and never put it in pure water. I just change the battery once every 6 months if it's being used a lot.

My bluelab tds pen is even older. I bet I've had it going on 10 years? I like to use ceramabrite stovetop cleaner to clean the electrodes. It's cheap, Its just the right polishing grit and doesn't leave any residue.

 

[Ikkt]

Ja, you normally don't need to, I just made it part of my yearly maintenance. And the Greisinger electrodes have a poorly covered port for refills and pressure equalisation when you do long term measurements, so there's always a little cristalisation and loss of electrolyte. Proven but not the best design I could think of...

Over here it's a real pain to find unscented scrub stuff (what's it called in English?) like bluelab advises, so I just used very fine grit sandpaper to clean my truncheon meter.
Is the ceramabrite scented?
And has the normal BL tds meter graphite electrodes like the truncheon?
Holds up just fine too, except the battery cap getting strange cracks. May be cause I used it to beat an ass**** that wouldn't want to leave my home a couple years ago. Multifunctional ;)

 

[Dirtbag]

Ja, you normally don't need to, I just made it part of my yearly maintenance. And the Greisinger electrodes have a poorly covered port for refills and pressure equalisation when you do long term measurements, so there's always a little cristalisation and loss of electrolyte. Proven but not the best design I could think of...

Over here it's a real pain to find unscented scrub stuff (what's it called in English?) like bluelab advises, so I just used very fine grit sandpaper to clean my truncheon meter.
Is the ceramabrite scented?
And has the normal BL tds meter graphite electrodes like the truncheon?
Holds up just fine too, except the battery cap getting strange cracks. May be cause I used it to beat an ass**** that wouldn't want to leave my home a couple years ago. Multifunctional ;)

Yeah the ceramabrite is unscented. I've used the same small bottle that came with my new stove for a couple years now, but you can buy it in the cleaning supplies isle at any grocery store. And yes the pen has the same graphite electrodes as the truncheon. Ive owned both but lent the truncheon out and never got it back..

 

[jumpincactus]

PH of RO water
Neutral pH is defined as 7.00, but RO water typically shows a pH of between 5.00 and 6.00. .....Given that the pH scale, like the Richter scale for earthquakes, is logarithmic, that means that pH 5.00 water is actually 100 times as acidic as pH 7.00 water.

 

[Dirtbag]

PH of RO water
Neutral pH is defined as 7.00, but RO water typically shows a pH of between 5.00 and 6.00. .....Given that the pH scale, like the Richter scale for earthquakes, is logarithmic, that means that pH 5.00 water is actually 100 times as acidic as pH 7.00 water.

That is true. But since it's an infinitely small amount of carbonic acid and other negatively charged anions that drop the ph to that level, it has almost zero buffer. There is almost no naturally occurring positively charged cations in there to counteract the acids which is why it's so low. Despite being nearly devoid of ions.

As an example take an equal volume of RO with a ph of 5, and a mixed nutrient solution with an ec of 1.8 and a ph of 5. Which one is going to take more ph up to get to 6.2?