Well Water PH Flocuation

[wobdee]

Last year my water report from Ward Labs had my PH at 7.4. This morning I had my PH tested locally and it came back at 6.85. Does this seem like a normal flocuation? I ran it through my water calculator and it doesn't drop my mash PH much, only .01 less, does that sound about right?

 

[mabrungard]

Water pH has virtually no effect on brewing performance. You need to be testing the more important parameters such as calcium content and alkalinity. Those probably aren't changing very much if your well isn't under the influence of surface water inflow.

 

[peterj]

I'm not sure if it's normal, but since it's well water I wouldn't expect the pH to be consistent and regulated like city water. But, your starting water pH doesn't really matter that much. It's all about the buffering capacity and minerals in the water.

 

[grathan]

I know measuring PH yourself can be fairly accurate, but what about Wards Lab's technique. Is it some automated machine that a $8/hr tech has to be relied on to change syringe and glassware between test batches? Point being for the cost of two tests you would own a PH meter already? I sent Wards 2 samples from the same tap and one was 7.7 and the other was 8.1

0.01 on mash ph isn't cause for concern though.

 

[wobdee]

Thanks guys. I've been brewing for many years and understanding water chemistry is kind of the last frontier to me to really fine tune my brews.

 

[ajdelange]

An immigrant from an eastern land receives a monthly check from an investment is his former homeland and deposits it in his U.S. bank each time. He notices that some months they credit him $100, sometimes $110, sometimes $98. So he asks the teller why this is and the guy responds 'Fluctuations'. Our hero, quite outraged, responds 'Well, fluck you too, roundeyes'.

 

[trentm]

I sent Wards 2 samples from the same tap and one was 7.7 and the other was 8.1

Interesting. How did the brewing minerals compare?

 

[grathan]

Surprisingly similar.

 

[ajdelange]

Last year my water report from Ward Labs had my PH at 7.4. This morning I had my PH tested locally and it came back at 6.85. Does this seem like a normal flocuation?

It's not probably fluctuation in the source but rather the way in which the samples were handled between collection and the measurement. I'm guessing that you are on a well in a mesic region. It is usual, in such places, for soil bacteria to produce enough carbon dioxide to lower the pH into the 6's because the partial pressure of CO2 underground is a lot higher than it is in the atmosphere. Water coming from such wells is, thus, supersaturated with respect to CO2 and loses it to air in the same way (but not as dramatically) as when a beer bottle is opened. When that happens the the pH rises and as a result some of the CO2 converts to bicarbonate increasing the alkalinity. Over a small range of pH (6.85 - 7.4) the conversion to bicarbonate approximately balances the CO2 loss with the effect that the alkalinity of the water doesn't change very much.

So all that is happening, I think, is that your water is losing a little more CO2 on its way to Ward Labs than it does during the trip to the hardware store or water treatment supplier. But I'll also note that the pH measurements made in a 'free' water test usually are very crude.

I ran it through my water calculator and it doesn't drop my mash PH much, only .01 less, does that sound about right?

As several people have pointed out it is the alkalinity of the water that determines the pH of the mash and as the alkalinity doesn't change much the mash pH would not be expected to change much either.