[Robert]

I'm regretting buying a pH meter that needs 4.0, 7.0, and 10.0 calibration solutions. They're not available in sachets, making ongoing use much more expensive.

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If your problem is getting the 10.0 in sachets, and you only use your meter for brewing, no problem.   You don't need to do the full 3 point calibration, just do a two point at 4.0 and 7.0.  The instrument only needs to be calibrated bracketing the range in which it will be used. 

[Craig Hairrell]

Strange. Last time I looked, most of the sachets were for values a bit off of 4.0 and 7.0, but now I see plenty!

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[denny]

I'm regretting buying a pH meter that needs 4.0, 7.0, and 10.0 calibration solutions. They're not available in sachets, making ongoing use much more expensive.

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I buy mine in individual sachets, so I know they're out there.

[KellerBrauer]

I'm regretting buying a pH meter that needs 4.0, 7.0, and 10.0 calibration solutions. They're not available in sachets, making ongoing use much more expensive.

Sent from my Pixel 3a XL using Tapatalk

If your problem is getting the 10.0 in sachets, and you only use your meter for brewing, no problem.   You don't need to do the full 3 point calibration, just do a two point at 4.0 and 7.0.  The instrument only needs to be calibrated bracketing the range in which it will be used.

Bingo!  Calibrate in the range you need most.

[narvin]

So i picked up a new box of the 4.01 and 7.01 sachets and tested my old solutions.



One expired, one about to expire.  They were open for at least 3 years, stored somewhere between 60 and 80, sometimes in the light.

Old 7.01 solution: 7.05
Old 4.01 solution: 3.95

Honestly I expected the opposite due to CO2 absorption, but the drift wasn't really that far.  Given that it should be deriving a linear slope from these measurements, it might be dead on in the mash pH range.  More mysteries of science!

[hopfenundmalz]

I need to do the same test with my new and old solutions.

[KellerBrauer]

I need to do the same test with my new and old solutions.

+1

I’ll do the same.  Great information narvin!

[KellerBrauer]

So i picked up a new box of the 4.01 and 7.01 sachets and tested my old solutions.



One expired, one about to expire.  They were open for at least 3 years, stored somewhere between 60 and 80, sometimes in the light.

Old 7.01 solution: 7.05
Old 4.01 solution: 3.95

Honestly I expected the opposite due to CO2 absorption, but the drift wasn't really that far.  Given that it should be deriving a linear slope from these measurements, it might be dead on in the mash pH range.  More mysteries of science!

Out of curiosity, how much did you pay for the buffers and where did you find box quantity?

[narvin]

https://www.amazon.com/gp/aw/d/B01N9MB9O4

https://www.amazon.com/gp/aw/d/B01MR0RIX7

[KellerBrauer]

https://www.amazon.com/gp/aw/d/B01N9MB9O4

https://www.amazon.com/gp/aw/d/B01MR0RIX7

Thanks narvin!

[goose]

You can also find hem at lab supply houses.  I buy mine in 500 ml bottles and use them within a year (which the bottle lists as the expiration date).  The difference you see from old solution, per Narvins post, isn't enough to worry about, IMHO.

Also I only use 4.0 and 7.0.  I see no need to do the three point test with the 10.0 buffer.

[hopfenundmalz]

I got every thing out today to add to the discussion.Milwaukee MW 101 meter. Adjusted temp to 20C (68F).
New General Hydroponics solutions calibrated to  7.00 and 4.00
Aldon corp solutions, maybe 3 years old.  6.85 and 4.08
Milwaukee solutions exp date 9/2016. 6.80 and 4.92
Really old Milwaukee sachets unopened exp 3/2019. 6.83 and 3.99

Recheck on calibration with new General Hydroponics solutions 7.01 and 3.99

This is what i just measured. My conclusion is to buy solutions more often. 
 

[dmtaylor]

I got every thing out today to add to the discussion.Milwaukee MW 101 meter. Adjusted temp to 20C (68F).
New General Hydroponics solutions calibrated to  7.00 and 4.00
Aldon corp solutions, maybe 3 years old.  6.85 and 4.08
Milwaukee solutions exp date 9/2016. 6.80 and 4.92
Really old Milwaukee sachets unopened exp 3/2019. 6.83 and 3.99

Recheck on calibration with new General Hydroponics solutions 7.01 and 3.99

This is what i just measured. My conclusion is to buy solutions more often. 

Thanks for sharing your experience!  Seems to confirm what we were thinking.

[mabrungard]

I have 4 and 7 solutions from Hanna and they have an expiration date in 2021 and I’ve had them for about 2 years already. So it appears that reputable solutions have something like 3 to 5 years life.

[hopfenundmalz]

I have 4 and 7 solutions from Hanna and they have an expiration date in 2021 and I’ve had them for about 2 years already. So it appears that reputable solutions have something like 3 to 5 years life.

My take away was how much drift can you abide by.