Mash PH is Very Low with BIAB - Numbers just don't make any sense

[Adam Switzer]

I do full volume BIAB. I start with RO water. I have measured the TDS of the RO and it is typically less than 3PPM, so I am pretty sure it is truly RO water. I use Bru'n Water spreadsheet and the new BeerSmith water tool to calculate my salt additions. Both are usually close to each other. I add the salts to the RO water before adding the grains bring it to mash temp and wait 20 minutes before pulling a sample to measure. I let the sample cool to room temp and measure with my digital meter and the cheap strips. Both measurements are similar between 4.6 and 4.8 pH. I have also read that lower pH typically increases the OG and FG, but my OG is usually spot on but my FG is always way below the predicted. That could be caused by other factors. But I just don't know why my pH is so low in the mash. Below are the last 3 brews I have done.

8.83 gallons of RO
2.6g Gypsum, 3.9g CaCl, 2.6g Epsom
7lbs 2 Row, 1lb white wheat, 0.5lb dextrin malt, 0.5lb acid malt
Predicted ph 5.4, measured ph 4.6

9.07 gallons of RO
2.4g Gypsum, 4.2g CaCl, 3.1g Epsom
6lbs 2 Row, 5.3lbs wheat malt, 0.5lbs Carapils, 0.5lbs Munich Malt
Predicted ph 5.6, measured ph 5.1

9.16 gallons of RO
2.5g Gypsum, 4.7g CaCl, 1.4g Epsom, 0.8g Baking Soda
6.8lbs Munich Malt, 5lbs 2 Row, 1.8lbs Vienna
Predicted ph 5.4, measured ph 4.8

 

[Silver_Is_Money]

The "measured" pH values you are getting from your pH meter are not at all likely to be correct. They are off on the low side by a good margin. pH strips are to blame here, but if your meter is somehow confirming the pH strips, it is also to blame. pH strips are notoriously useless.

 

[yourlastchance89]

Do you calibrate your pH meter before brewing?

 

[bracconiere]

Do you calibrate your pH meter before brewing?

and i'll say, i never had any luck with 'predicting' mash ph. i just get the mash going measure ph in the cooler with the grain and all, and go from there...either epsom salts to lower it a little, phosphoric acid a lot....or potassium bicarb to raise it...(i like the potassium for the mineral content!)

And on the current trend of comments, besides calibrating what does the meter read in the cal solution out of cal mode?

 

[yourlastchance89]

and i'll say, i never had any luck with 'predicting' mash ph. i just get the mash going measure ph in the cooler with the grain and all, and go from there...either epsom salts to lower it a little, phosphoric acid a lot....or potassium bicarb to raise it...(i like the potassium for the mineral content!)

And on the current trend of comments, besides calibrating what does the meter read in the cal solution out of cal mode?

I'm not sure what pH the storage fluid is but the meters are designed to be calibrated at 2 different pH levels to get the most accurate reading at 7.0 and 4.01. Mine always requires some adjustment every brewday. You should also be reading wort samples that are room temp for the most accurate reading.

 

[ScrewyBrewer]

I do full volume BIAB. I start with RO water. I add the salts to the RO water before adding the grains bring it to mash temp and wait 20 minutes before pulling a sample to measure.

@Adam Switzer when you add the salts to your RO water are you waiting at least 20-30 minutes before combining your grains with it in the mash?

 

[balrog]

OP, I put in that first bill with RO (nothing in water) on Martin's ver 5.4 and it predicted pH of 5.02. I will admit that I guessed at the Lovibond of the individual grains.

He said the latest ver is better with thin, BIAB mash water ratios.

 

[bracconiere]

I'm not sure what pH the storage fluid is but the meters are designed to be calibrated at 2 different pH levels to get the most accurate reading at 7.0 and 4.01. Mine always requires some adjustment every brewday. You should also be reading wort samples that are room temp for the most accurate reading. View attachment 592455

as far as storage fluid, i was just recently told that it's a 3M KCl solution?

i've actually read that the gold standard 5.2 is at mash temp, not room temp? i don't know, ph doesn't matter much to me anyway, just the difference between 79-80% efficiency and 83-85%...

As long as it's not so acidic i have to use wine yeast instead of ale...

and i hate it when i can't bite my tongue and post in a ph thread, lol just this morning i was trying to figure out how to make a certain ph NaOH solution and google barraged me with logarithms!
(and i haden't even finished my first cup of coffee!)

 

[Adam Switzer]

Do you calibrate your pH meter before brewing?

I always calibrate the meter first thing on brew day. There is no calibrate mode. You just adjust the screws to read the value of the calibration liquid.

I'm not sure what pH the storage fluid is but the meters are designed to be calibrated at 2 different pH levels to get the most accurate reading at 7.0 and 4.01. Mine always requires some adjustment every brewday. You should also be reading wort samples that are room temp for the most accurate reading. View attachment 592455

I always allow the liquid to cool before I measure the PH. The strips and the meter both measure low which leads me to believe that they are both correct. I just bought a new MW101 PH meter. I will test it out in the next couple of days.

@Adam Switzer when you add the salts to your RO water are you waiting at least 20-30 minutes before combining your grains with it in the mash?

I add my salts to the water the night before to ensure they are completely dissolved.

 

[Adam Switzer]

OP, I put in that first bill with RO (nothing in water) on Martin's ver 5.4 and it predicted pH of 5.02. I will admit that I guessed at the Lovibond of the individual grains.

He said the latest ver is better with thin, BIAB mash water ratios.

I use the free version. Maybe I should donate and get V5.4. The Lovibond on the first Recipe is all <3.

 

[pnewgard]

Double crush?

 

[Adam Switzer]

Double crush?

I do not double crush. I was considering this for the next go around, but my mash efficiency is always greater than 85%, and my OG is usually within predicted +/- 2 gravity points. Do you think this would make a difference in my pH?

 

[pnewgard]

No, sorry, that's great results for efficiency!