Author Topic: "Measured" vs. "Reported" pH for Water Calculator  (Read 3181 times)

Offline philm63

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"Measured" vs. "Reported" pH for Water Calculator
« on: June 22, 2014, 08:09:35 AM »
Just got my water report for this year from Ward Labs and it says my pH is 7.9. When I measure my water I get pH 6.0. I use my tap (city) water, very low minerals, filtered (under-sink unit), and I measure it for pH before I brew each time. pH meter is an MW101, and I use a two-point calibration before each use so I'm pretty confident my readings are solid.

I'm most interested in knowing which is more appropriate for a water calculator such as Bru'n Water. Seems I should input my actual measured value and not what the report tells me. Does this make sense?
« Last Edit: June 22, 2014, 08:12:43 AM by philm63 »
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Offline grathan

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Re: "Measured" vs. "Reported" pH for Water Calculator
« Reply #1 on: June 22, 2014, 01:19:06 PM »
I have a mw101 and it struggles with low mineral content, but since you've claimed your readings to be solid why not just go with them?


It's possible there was impregnated base type of soap in the container you shipped?


If by filter you  mean RO under sink unit? sometimes they can effect PH in wierd ways by removing certain ions that could make their way back into the water while shipping.


I've worked in a lab before. I know they struggle with contamination and erroneous results and certainly operator laziness.


Certainly you could compare your mash ph expected vs. actual and see which one comes closer.

Offline philm63

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Re: "Measured" vs. "Reported" pH for Water Calculator
« Reply #2 on: June 22, 2014, 03:14:42 PM »
It's possible there was impregnated base type of soap in the container you shipped?

If by filter you  mean RO under sink unit?

Rinsed the container sent by Ward labs for several minutes under the running filtered water to ensure the container assimilated as best it could to the water that was going for a ride in it. Shook it several times to ensure there were no risiduals left behind, then filled as per my normal protocol for this test.

The water filter is a point-of-use activated cabon filter - no RO. I use it to remove the traces of chlorine that vary in the city supply - also hit it with Cambden as a precaution.

My water is very low-mineral, and I was not aware of any difficulties measiring pH in that situation - I'll be sure to look into this further to better understand this. I do know now that there may be dissolved CO2 as a result of my water being pressurized in the pipes - possibly enough to give me a lower reading for a short time - it was suggested by a water expert to let it sit for a while and if the pH goes up a little, there likely was dissolved CO2.

I also learned that the pH in your brewing water has little to do with mash pH (well, as long as it is in range for "normal" drinking water, that is...) - it's more about the ions in the water, and the ions you add when making your water adjustments that drive the mash pH along with the specific grain bill. There really is so much to this water thing.
On Tap: Oatmeal Stout, IPA
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On Deck: Kolsch

KernelCrush

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Re: "Measured" vs. "Reported" pH for Water Calculator
« Reply #3 on: June 22, 2014, 03:15:08 PM »
Phil, I asked Ray Ward about this same thing on my last test.  I always get a lower reading with my meter compared to his report too.  He said that if the container was less than full to the brim and/or was left open by the lab, the pH will rise with O2 exposure.  He says trust your meter too.  I have the same one.

Offline philm63

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Re: "Measured" vs. "Reported" pH for Water Calculator
« Reply #4 on: June 22, 2014, 06:01:03 PM »
Thanks, Kernel - reassuring to know.
On Tap: Oatmeal Stout, IPA
Fermenting: Air
On Deck: Kolsch