RO Water - starting with lower pH

[Anavrin215]

Due to my local water (philly), I've shifted to using full RO water and have been having a hard time with dialing it in.

One of the things that throws me off is stripping back my starting pH from the average 6.8-7.2 to about 5.7-5.8~

Recently, I tried my stout recipe (grain bill & mash below) and have consistently been met with batch pH's dropping too low; fyi, I'm using an Apera PH60 reader that's pretty reliable and calibrated often.

Because of the low pH issues, in a recent batch I decided to add my roasted grains (chocolate & black pat) just before vorlauf and sparge. In previous batches, I'd mash with the dark grains in, so wanted to see how this turned out.

Note, b/c I wasn't adding the dark grains until close to sparging, I didn't add any baking soda or chalk to help boost the pH. Beersmith, considering just the Maris & flaked barley, was estimating 5.7, which I know is on the high side for sure, but I wasn't going to add any lactic, because I knew adding the dark grains would bring it down somewhat, even if adding towards the end of the mash. I did use the full volume of water as if using all the grain, so my liquor to grist ratio was 2.9 l/kg (as oppose to the typical 2.6 l/kg) for the majority of the mash.

I only treated the 3.16gal of mash water with .5g CaCl and 1.5g Gypsum.

When I pulled a mash sample and cooled – this was before the dark grains were added – the pH was 5.34, so significantly lower than anticipated. Post boil pH was then down to 5.2.

It's now fermenting away (I used 1x packet of Nottingham @62deg.), and the pH has dropped after 3 days to to 3.8. I know stouts are generally on the lower side, but I'm afraid it'll go below 3.7 at this rate, and not be pleasurable to drink. I feel if the mash pH was a bit higher, and therefore the starting pH into the ferm would be higher, this wouldn't be dropping so low. I don't believe there's any type of bacteria issue driving the pH down in the fermenter – I thoroughly CIP'd and sani'd my fermenter / equipment just before the brewday.

Would love any thoughts on why there's that discrepancy in the mash, or if you brew with full RO water, how do you treat your water when using dark grains?

Recipe (for 6.5 gal batch):
7# Maris Otter
2# Flaked Barley
12oz chocolate (450)
6oz Black Pat Malt (650-700)

Single infusion mash at 154, 60 min

 

[HighVoltageMan!]

the pH has dropped after 3 days to to 3.8

That low pH is a function of the fermentation more than the mash. You should be @ 4.0 to 4.3 A 5.2 ph post boil is a little low for a stout, 5.3-5.4 would be better.

A good fermentation will produce relatively stable finish pH's, each yeast will hit what I like to call it's "sweet spot". When I pitch my lagers, I shoot for a post pH of 5.1, the finish pH is almost always 4.3, even when I pitch a little high like 5.2-5.3. The yeast will excrete acids to lower the pH to it's optimum level to aid in transferring nutrients across it's cell membrane. The reason I pitch at such a low pH is for yeast health, it's easier on the yeast to only have to drop from 5.1 to 4.3 than from 5.3 to 4.3. If the pH is too high, the yeast may not be able to drop the pH as low as it should. Some yeast produce more acids than others. WLP029 can drop the pH to 3.9

There are a number of things I would check. First make sure the carbon dioxide is out of solution when the pH is measured. The other is to consider blended the RO water with your local water to bring up the alkalinity to an acceptable level, you could also add baking soda or pickling lime. Be careful with baking soda, it works really well, but it brings sodium with it and saline flavor if the levels get too high. Water calculators can help with this.

Lastly, wait until the beer is done and taste it, your meter may have misled you and everything is totally fine.

 

[tracer bullet]

When I pulled a mash sample and cooled – this was before the dark grains were added – the pH was 5.34, so significantly lower than anticipated.

FYI, this is a good time to measure pH. Prior to this RO water pH is finicky and not worth worrying about.

As for 5.34, that seems totally fine. Sure you can dial it in but this certainly wouldn't be a concern at all.

 

[Bassman2003]

In any discussion about pH readings, I bring up the question about your calibration solution. Is your pH calibration solution fresh and within expiration dates? The liquid stuff is 6-12 months tops from creation. This really makes a big difference in accuracy.

 

[Anavrin215]

FYI, this is a good time to measure pH. Prior to this RO water pH is finicky and not worth worrying about.

As for 5.34, that seems totally fine. Sure you can dial it in but this certainly wouldn't be a concern at all.

Yeah, I know it's not bad at all, but considering then dark grains are added to it (at vorlauf & before sparge), it's just that issue of continuing to ferment down to the <3.8 area. I'm wondering if I at least go into the boil with a higher pH (5.4-5.5), I'll at least stand a better chance ending at that 4.0~ spot considering the style.

 

[Anavrin215]

In any discussion about pH readings, I bring up the question about your calibration solution. Is your pH calibration solution fresh and within expiration dates? The liquid stuff is 6-12 months tops from creation. This really makes a big difference in accuracy.

Makes sense; the 7 & 4 buffer solution are about 4 months old, so I'm not sure if those are the culprit.

 

[marc1]

It's possible that your lots of grain contribute differently to the mash pH than the defaults in the program for them.

 

[beren]

Try the bru’n water spreadsheet if you haven’t abs see if that better estimates reality.

 

[Anavrin215]

Try the bru’n water spreadsheet if you haven’t abs see if that better estimates reality.

I tried that - that suggested I should be at 5.5 during my mash (of the lighter grains), and it was at that low 5.3 reading when cooled and measured.

 

[Indian_villager]

I tried that - that suggested I should be at 5.5 during my mash (of the lighter grains), and it was at that low 5.3 reading when cooled and measured.

I too use RO for all my brewing and for stouts I actually mash everything but the dark grains and target ~5.35 15mins into the mash @Mash temperature. From there I add the dark grains during mashout with enough baking soda to bring the pH to 5.5. I use Bru N water to figure out how much salts and baking soda to add, and it honestly has only been a few thousandths off my measured value.

 

[Bassman2003]

Be careful with pH numbers and mash vs room temps. The brewing world standard is room temp readings which are roughly .25 - .35 lower than mash temp readings. So the stated 5.35 (mash temp) target is actually ~ 5.1 in room temp standards which is pretty low. the dark grains will drive it lower once added. I would say you would want to aim for pH 5.35 or higher measured at room temp. Kunze is in the ballpark of pH 5.5 - 5.6 (at room temp).

 

[marc1]

I tried that - that suggested I should be at 5.5 during my mash (of the lighter grains), and it was at that low 5.3 reading when cooled and measured.

0.2 isn't that far off. The software runs on generic assumptions about the malt and how it will act in the mash; it is pretty amazing that it works as well as it does. Take note of the grains used and the readings and adjust accordingly for next time.

 

[Anavrin215]

Be careful with pH numbers and mash vs room temps. The brewing world standard is room temp readings which are roughly .25 - .35 lower than mash temp readings. So the stated 5.35 (mash temp) target is actually ~ 5.1 in room temp standards which is pretty low. the dark grains will drive it lower once added. I would say you would want to aim for pH 5.35 or higher measured at room temp. Kunze is in the ballpark of pH 5.5 - 5.6 (at room temp).

That 5.35 is my sample when it was adjusted (cooled) to room temp, which yes, is still lower, as I was shooting for 5.5 - 5.6 knowing that adding my dark grains would drive things down in the kettle.

 

[Bassman2003]

Cool. I am on a crusade to have everybody state room temp or mash temp when they speak about pH. It is a large enough difference that it needs to be pointed out to avoid confusion.

 

[DBhomebrew]

Cool. I am on a crusade to have everybody state room temp or mash temp when they speak about pH. It is a large enough difference that it needs to be pointed out to avoid confusion.

You're not wrong, but...

When I pulled a mash sample and cooled – this was before the dark grains were added – the pH was 5.34, so significantly lower than anticipated.

That was post #1

 

[Bassman2003]

Sorry, I should have used quotes as I was replying to Indian_villager.

 

[Indian_villager]

Sorry, I should have used quotes as I was replying to Indian_villager.

I truly understand your crusade on the listed temperature as this is something I stumbled over in another thread. I am working off the following byo article which lists both target pH at mash and room temp. Using the pH values I listed at mash temp has lead me to good efficiencies so take my anecdotal experience with a grain of anhydrous salt at STP.
https://byo.com/mr-wizard/setting-record-straight-mash-ph/

 

[Gadjobrinus]

This came up on another site and I've always felt the following from Houghs, Briggs and Stevens's Malting and Brewing Science helpful:

A major difficulty follows from the habit of measuring the pH of worts or mashes at room temperature and assuming that these values apply at higher temperatures, when they do not (Hopkins and Krause, 1947). Weak acids, like water (see Appendix), dissociate more as the temperature rises and so the pH values of their solutions fall, like the pH values of mashes (Table 4.8). Thus at 65C (149F) the pH of a wort is likely to be about 0.35 pH unit lower than at room temperature and 0.45 lower at 78C (172.4F). As the temperature of a mash changes (decoctions, temperature programming, sparging) so will the pH. These differences are significant, yet in many reports it is unclear if pH values have been determined at wort- or mash-temperatures or on cooled samples. Probably the latter is most usual. The pH optimum of alpha amylase, determined at room temperature, is about pH 5.3, but its optimum estimated from mashing experiments is often reported to be about 5.7. This error is due to the pH having been determined on the mash after it was cooled, when the pH had risen. Because of this difficulty the pH optima of changes occurring in mashes are a little uncertain.

Mashing pale malt in distilled water usually gives a wort with a pH of about 5.8 - 6.0, this value being maintained by the buffer substances (including phosphates and proteins) from the grist. Infusion mashes are best carried out at pH 5.2 - 5.4 (mash temperature), and so will give cooled worts with pH values of about 5.5 - 5.8. It has been recommended that decoction mashes should not give worts with pH values less than 5.5.

 

[Bassman2003]

Yes. I just want everybody on forums to at least state what temperature their reading was taken at so we can all be on the same page. Or better yet, just use room temps as that protects your pH probe and is the brewing industry standard.

 

[jerrylotto]

The only times I pay attention to pH is water (before the mash) and15 minutes into the mash and if it is on target (5.4-5.5) on that second check (or adjusted to hit those numbers) I don't worry about it after that point. If it is swinging wildly it means you don't have enough of a buffer concentration, typically bicarbonate in a mash.

 

[Hoochin'Fool]

As someone facing the same problem of needing to switch to RO or distilled water, my plan was to just add Baking Soda to my strike water, at whatever amount Brewer's Friend tells me to use, to get my predicted mash pH up to 5.5 -- any reason NOT to do that? For the big, roasty stouts, anyways.

 

[jerrylotto]

As someone facing the same problem of needing to switch to RO or distilled water, my plan was to just add Baking Soda to my strike water, at whatever amount Brewer's Friend tells me to use, to get my predicted mash pH up to 5.5 -- any reason NOT to do that? For the big, roasty stouts, anyways.

That is what I usually do

 

[beren]

pH up to 5.5

Not every beer should be 5.5. It depends on the grain bill.

 

[jerrylotto]

Not every beer should be 5.5. It depends on the grain bill.

I was talking about mash pH - that takes the grain bill into account.

 

[Hoochin'Fool]

Not every beer should be 5.5. It depends on the grain bill.

Every big roasty stout should be!

 

[beren]

Sure but pale beers should be lower. Down to 5.2 even.

 

[DBhomebrew]

All y'all talking room temp?

 

[beren]

I am. https://www.brunwater.com/water-knowledge

 

[Bassman2003]

I run pale beers at pH 5.5-5.6 That is what the famous brewing texts talk about. Dropping it down to 5.2-5.1 at the end of the boil before whirlfloc is recommended for best performance and help the yeast.

 

[jerrylotto]

I run pale beers at pH 5.5-5.6 That is what the famous brewing texts talk about. Dropping it down to 5.2-5.1 at the end of the boil before whirlfloc is recommended for best performance and help the yeast.

Exactly. Too high of a mash pH is a problem for efficiency and conversion and can extract tannins, but too low of a mash pH will simply thin out the mouthfeel. Mashing all about enzymatic reactions and has nothing to do with yeast. Adjustments after the boil are another matter entirely.

 

[jerrylotto]

Exactly. Too high of a mash pH is a problem for efficiency and conversion and can extract tannins, but too low of a mash pH will simply thin out the mouthfeel. Mashing all about enzymatic reactions and has nothing to do with yeast. Adjustments after the boil are another matter entirely.

That said, yeast grows and multiplies much more rapidly at a pH higher than 5.0 (5.5 is optimal), but fermentation is more efficient if the pH reading is below 5.0.