First test mash - need help adjusting for full volume

I just purchased my first PH meter (thanks AJ, I went with the new Hach meter). I did a test mash using 1 pound proportionately of my grain bill and 1.3 quarts of distilled water. I tested the mash ph at 15 minutes and got a reading of 5.35. The grain bill is:

Maris Otter - 80.5%
Crystal 20l - 8.4%
Crystal 77l - 6.6%
Biscuit - 4.4%

When I put that grain bill into Bru'n Water, it comes up with an estimate of 5.45, using 100% RO water and no water adjustments. When I adjust my 100% RO water in Bru'n Water to get close to the water profile I want - the amber bitter profile - the estimated ph in Bru'n Water changes to 5.3.

My question - since my measured test mash ph was 1.00 lower than Bru'n Water's estimate, do I assume that with the water adjustments, it will be 1.00 lower, too, so I need to shoot for 1.00 higher than my desired final ph? If that's the case, how would I raise the ph 1.00? I assume I would add pickling lime and reduce the other additions as appropriate.

I'm curious if AJ or Martin feel that 5.45 vs 5.35 is within the repeatability of this experiment.

Which one did you get? The Pocket Pro Plus?

From what you're writing I can see a pH difference of 0.1, not 1.

Martin allows for some ions in his RO preset, this could account for a portion of the delta in the estimate, as you mashed with DI. It is also possible the distribution of the crystal was slightly off... Difficult to measure scaled down that far. For your test mash, I would take a measurement right away dough in, at 5 minutes, at 15 and again at 45/60 minutes.

I assume the pH meter is calibrated...

As for giving you a recommendation on raising the pH by 0.1 (not 1.0 as you indicated), we would need the entire mash volume. You can calculate the necessary amount easily in Bru'n... simply hit your target pH solely with gypsum and calcium chloride additions (I assume a very small amount given the recipe) and then add enough pickling lime to raise the mash pH by 0.1. When measuring your salts, hold the lime aside and use only if you think you need to. I would suggest adding no alkalinity at first. 5.3 is a fine mash pH, and I would use the lime only if the mash pH drops below 5.2. Measure pH after dough in... And again at 5 minutes. Adjust then if required.

Thanks for the help. Yes, I meant 0.1, not 1.0.

I wondered after I posted if using distilled water instead of RO for the test mash would account for part of the difference. I'll make sure I get my water for my brew session from the water machine at the store before I do my test mash.

You suggest taking readings at various times during the test mash. How do I translate multiple readings into an adjustment on my full mash? I guess I mistakenly thought from my limited research that about 15 or 20 minutes into the mash is where you want to see your pH at the ideal number for the style you are brewing. I'm new to water adjustment, so I appreciate the advice.

IslandLizard said:

Which one did you get? The Pocket Pro Plus?

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Yes, I got the Pocket Pro Plus. My first meter so I have nothing to compare it to, but so far so good.

You are correct that correction earlier is better. Correction after the first 15-20 minutes is less effective, bit conversion does continue until your temperature exceeds 168f. As you learn to brew with the pH meter take more measurements than less, which will illustrate what happens in the mash.

You would want to keep notes and make the adjustment first thing for the next batch.

CadiBrewer said:

I just purchased my first PH meter (thanks AJ, I went with the new Hach meter).

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Did you do the stability check at https://www.homebrewtalk.com/f128/ph-meter-calibration-302256/ ? You can really help the community by letting us know how your sample of this meter performs.

CadiBrewer said:

I did a test mash using 1 pound proportionately of my grain bill and 1.3 quarts of distilled water. I tested the mash ph at 15 minutes and got a reading of 5.35. The grain bill is:

Maris Otter - 80.5%
Crystal 20l - 8.4%
Crystal 77l - 6.6%
Biscuit - 4.4%

When I put that grain bill into Bru'n Water, it comes up with an estimate of 5.45, using 100% RO water and no water adjustments.

Click to expand...

That's about as good as you can expect a calculator that doesn't know anything about the malts you have in front of you except their color to do. That's a good estimate. But I'd let the test mash sit a bit longer. It is very important to stir it too as it is that which lets the dissolved acid from one grain reach the dissolved base from another. 5.35 seems a bit low. I'd expect something closer to what Bru'n water told you. Also be aware that there is a learning curve with pH meters. That's why it is very important that you do the cal and stability checks. You need to really know how to use a meter before you put total reliance in it. Just practice with calibration, calibration checks and measurements will do.

CadiBrewer said:

When I adjust my 100% RO water in Bru'n Water to get close to the water profile I want - the amber bitter profile - the estimated ph in Bru'n Water changes to 5.3.

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Adding the minerals thus causes the prediction to drop by 0.15. That's quite a large drop from just calcium addition but it is possible. Whether you will see such a drop depends on the phosphate and protein content of your malts and their buffering capacities vis a vis the model used by the spreadsheet. For a nominal mash it would take about 190 mg/L calcium content in the water to drop the pH of an RO mash that much.

CadiBrewer said:

My question - since my measured test mash ph was 1.00 lower than Bru'n Water's estimate, do I assume that with the water adjustments, it will be 1.00 lower, too, so I need to shoot for 1.00 higher than my desired final ph? If that's the case, how would I raise the ph 1.00? I assume I would add pickling lime and reduce the other additions as appropriate.

Click to expand...

Adding calcium and magnesium will lower the pH of your mash but unless you are adding a lot of calcium, not by that much. The idea of a test mash is to release you from dependence on the uncertainties of models. Thus you should do the test mash with the water you intend to brew with i.e. to see the effects of the water on the malts.

If, indeed, the pH drops to 5.3 or below you might want to raise the mash pH some. In that case, lime or a little baking soda would probably be your best bets. But then check the pH of the test mash with those added.

BackAlley said:

I'm curious if AJ or Martin feel that 5.45 vs 5.35 is within the repeatability of this experiment.

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A disagreement of 0.1 between a calculated pH and a measured pH represents, IMO and experience, a good match. However part of that disagreement may be attributable to pH measurement error. With the usual low cost meter instability could be a large part of 0.1 pH. We are all hopeful that this new meter may have brought that instability under control but the jury is still out. That's why I encourage OP to do the stability check.

Out of curiosity, I changed the RO water to distilled in Brun and ran the grain bill. It came up as estimated at 5.40. That compares to my test mash of 5.35. I figure that being new to the world of pH meters and testing, a delta of. 05 is well within my expected margin of error.

CadiBrewer said:

I wondered after I posted if using distilled water instead of RO for the test mash would account for part of the difference. I'll make sure I get my water for my brew session from the water machine at the store before I do my test mash.

Click to expand...

That isn't going to make much difference. Mineral content is low in both DI and RO water. You should, for best results, be doing the test mash with the water, treated as you intend to treat it, with which you plan to brew.

CadiBrewer said:

You suggest taking readings at various times during the test mash. How do I translate multiple readings into an adjustment on my full mash? I guess I mistakenly thought from my limited research that about 15 or 20 minutes into the mash is where you want to see your pH at the ideal number for the style you are brewing. I'm new to water adjustment, so I appreciate the advice.

Click to expand...

You aren't really looking for a number at a particular time so much as a pattern. If you dough in and find the first pH reading is 4.9, a second one 5 minutes later is 5.2 and others, at 5 minute intervals, of 5.3, 5.38, 5.40, 5.43, 5.50, 5.51, 5.52, 5.52, 5.52...you know that things are going well even though the first reading (4.9) might alarm you. If things settle out at 5.6 or 5.7 then you know you will want more acid. If they settle out at 5.1 then you will know you need less (or compensating base). The idea is to do the learning on test mashes rather than full mashes. Once you have a test mash that shows you the desired pattern you then just scale water, malt, acid, base, additions to the full mash and you should get from it pretty close to what you saw in the test mash.

ajdelange said:

Did you do the stability check at https://www.homebrewtalk.com/f128/ph-meter-calibration-302256/ ? You can really help the community by letting us know how your sample of this meter performs.

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I'll definitely do the stability test and report back my results. Anything I can do to partly return the favor of everyone helping me on this forum, I'm happy to do. Question about the stability check - can I pour a bit of each buffer into small cups and use these over the course of a two hour test, or should I be using fresh buffer solution for each reading?

This Hach meter is perfect for the stability check. Calibrate it per their instructions (i.e. put the buffer in the electrode cap) and at the conclusion of calibration with 4 buffer just leave that buffer in the cap. Start a timer. Set the meter in a tumbler or coffee cup or something and set it somewhere convenient where the temperature won't change much from the temperature you calibrated at. Write down time, pH and temperature every few minutes at first and then less frequently. Leave it this way for 24 hours checking every 15 minutes after the first couple of hours, then every hour after that and eventually every few hours, finally overnight. The meter turns itself off after a few min. of no activity and so you must turn it on after the longer intervals. You can turn it off after a reading if you want to extend battery life. Give a little shake to move new liquid into the area near the bulb before each reading. Wait a few sec. for the reading to restabilize if it changes when you do this.

The O-ring on the cap keeps buffer from leaking out and prevents loss of water by evaporation.

Note that in #13 I only mention the pH 4 buffer. If either slope of offset drifts the reported pH on pH 4 buffer will change detecting that. If you measure pH 7 buffer only offset drift is detectable (provided isoelectric pH is close to 7 as it should be). Thus pH 4 buffer alone is sufficient for a stability test. I guess I should change the Sticky to reflect that.