Phosphoric Acid vs Lactic Acid

I have a fresh bottle of phosphoric acid. I've never used it before, but I saw on Braukaiser's website that 0.1-0.135 ml would lower mash pH by 0.1, while the amount of lactic acid used for the same drop would be 0.125-0.21 ml.

I typically use 5 ml of lactic 88% in 5 gallons of sparge water. Can I assume roughly the same amount for using the phosphoric acid to start?

I was always under the assumption that you used lactic acid for the mash and phosphoric only if you treated sparge water.

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I'm hoping that there is a strength indication on that phosphoric acid, like 10% or 75%.

To get to the point, you can't assume the use of phosphoric will be like your use with lactic. The acid strength may be quite different.

There is a full-featured acidification calculator in Bru'n Water for those who wonder how much acid they should be adding to their water. That will enable Yooper to figure this problem out.

PS: you can use any type of acid you want for either mash or sparge.

mabrungard said:

I'm hoping that there is a strength indication on that phosphoric acid, like 10% or 75%.

To get to the point, you can't assume the use of phosphoric will be like your use with lactic. The acid strength may be quite different.

There is a full-featured acidification calculator in Bru'n Water for those who wonder how much acid they should be adding to their water. That will enable Yooper to figure this problem out.

PS: you can use any type of acid you want for either mash or sparge.

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I'm having trouble with your spreadsheet in OpenOffice, so I'm not using it at this point. I'm going to try libreoffice next.

My phosphoric acid is 10%. I supposed that is important!

I decided to try phosphoric acid in my sparge water as the lactic acid I'm using IS below the taste threshold at this point, but I was thinking about make a cream ale and I didn't want any "tang" to it at all. I do use acidulated malt in the mash.

Yooper said:

I decided to try phosphoric acid in my sparge water as the lactic acid I'm using IS below the taste threshold at this point, but I was thinking about make a cream ale and I didn't want any "tang" to it at all. I do use acidulated malt in the mash.

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In "Brewing Better Beer", Gordon Strong says (page 50): "Adding phosphoric acid is the easiest way to lower the pH of sparge water without adding undesirable flavors. Lactic acid is a distant second choice."

DeafSmith said:

In "Brewing Better Beer", Gordon Strong says (page 50): "Adding phosphoric acid is the easiest way to lower the pH of sparge water without adding undesirable flavors. Lactic acid is a distant second choice."

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That's where I was going with my poorly worded post. Fwiw, i've never had any discernible flavors from lactic acid in the mash, even in a cap, now sauermalz, that's a different story.


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Yooper said:

I'm having trouble with your spreadsheet in OpenOffice, so I'm not using it at this point. I'm going to try libreoffice next.

My phosphoric acid is 10%. I supposed that is important!

I decided to try phosphoric acid in my sparge water as the lactic acid I'm using IS below the taste threshold at this point, but I was thinking about make a cream ale and I didn't want any "tang" to it at all. I do use acidulated malt in the mash.

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Libre Office forked from OO when Sun got stupid. They are still pretty much the same code base.

Phosphoric acid is a very good choice for brewing use. It has the least flavor impact since there are already similar anions in the mash. Adding a few more does not alter the flavor. Lactic has a distinct taste that is certainly pleasant and desirable in some styles. The same can be said for sulfuric and hydrochloric. They are just more hazardous to handle. The whole issue of taste impact is contingent upon the amount of alkalinity you're having to deal with. If its a lot of alkalinity, then other forms of treatment are probably needed.

Lorena, I had poor impressions of OpenOffice also. I've been much more impressed with LibreOffice. Its almost like using real Excel. Bru'n Water should work well for you there.

Phosporic is more reactive and will drop the pH much quicker than lactic. pH is logarithmic as I am sure you know, but phos will drop the bottom out very fast. Use a couple drops in the water, don't add to the mash because you will all of a sudden be at 2.0 pH.

onthekeg said:

Use a couple drops in the water, don't add to the mash because you will all of a sudden be at 2.0 pH.

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What does this mean?

mabrungard said:

Lorena, I had poor impressions of OpenOffice also. I've been much more impressed with LibreOffice. Its almost like using real Excel. Bru'n Water should work well for you there.

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Thanks, Martin. I've had a few issues with LibreOffice and your spreadsheet as well, though. It allows me to input some things, others I cannot. But I'll keep playing with it. It's a great resource, and I'm hoping to use it ASAP!

I know it's a bit unusual to treat mash and sparge water separately, but I have two primary reasons for doing so. One is that I have highly alkaline water- HCO3 of 228 (total alkalinity as CaCO3 is 207). I've been diluting about 30-40% with RO water from the store but when I make a 10 gallon batch I'm finding that burdensome. Instead I haul 2 (2) gallon containers that are easy to carry and cost a total of $1.50. That works great for my 5 gallon batches, but for 10 gallon batches it's just not enough. Lately, I find that using the RO with some sauermaltz in the mash does the trick and the beer is better for it. I've been treated my sparge water with 5 ml of lactic acid for 8 gallons and it's been great.

The other reason is that I have a 14 gallon capacity in my HLT. So that means refilling the HLT anyway before the sparge. That means untreated water mixed with the treated water and I'm just not that smart. It's easier to treat the mash water right in the MLT and then add my acid to the sparge water in the HLT.

I bought some phosphoric acid because "everybody" says it's "better" as far as being able to use it and not hit a taste threshold before the alkalinity is in a better area, if I"m understanding correctly.

pH isn't linear, so you really can't say it will drop a specific amount for every given volume. As you probably already know, a pH difference of 1 (ie 5.4 vs 4.4) represents a 10-fold difference in acidity. Adding enough acid to drop the pH by 1.0 at a certain point will only drop it at 0.01 at another point, for instance.

And because water/wort samples will buffer differently from one another, it's difficult to predict.

I use 85% phosphoric in most of my beers (88% lactic in German styles, for the most part), and even at a slightly lower concentration, the phosphoric acid is a bit stronger.

Really though, AJ is the obvious guy to give you an answer for this, but I think his main point will be the same as mine - use a pH meter and measure as you go!

Ah, my water is highly alkaline as well. Not surprising yours is too. You on municipal or well water? My water comes right from Lake Ontario, so I know most people in the area have similarly crappy water.

I'm moving in a week to a place that uses well water though. Not sure if I'll need to continue using distilled water, but apparently I can submit samples to the city twice a week and get a report back, free of charge, which is something I definitely intend to abuse!

Yooper said:

Thanks, Martin. I've had a few issues with LibreOffice and your spreadsheet as well, though. It allows me to input some things, others I cannot. But I'll keep playing with it. It's a great resource, and I'm hoping to use it ASAP!

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Is his spread sheet a M$ dot xls or whatever the extension it is? OO/LO may have trouble importing it correctly. That is why they exist, to promote an open standard so this crap doesn't happen. If you can't input something into a cell it may be 'locked'. Try google and see if that helps.

emjay said:

Ah, my water is highly alkaline as well. Not surprising yours is too. You on municipal or well water? My water comes right from Lake Ontario, so I know most people in the area have similarly crappy water.

I'm moving in a week to a place that uses well water though. Not sure if I'll need to continue using distilled water, but apparently I can submit samples to the city twice a week and get a report back, free of charge, which is something I definitely intend to abuse!

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My cottage has a well loaded with iron so I don't use that water at all for brewing! But my house in town uses city water. It's really good tasting water, but hard and alkaline.

bigbeergeek said:

What does this mean?

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If you put it in the mash, it is much harder to mix in properly, whereas in the HLT it is much easier to have even mixing. Have you ever measured the temp variability in the MT? The pH will be just as variable.

onthekeg said:

If you put it in the mash, it is much harder to mix in properly, whereas in the HLT it is much easier to have even mixing. Have you ever measured the temp variability in the MT? The pH will be just as variable.

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Can't you just mix it with the mash water before mixing in the grains?

That is the best way, and I wasn't good at explaining.

The bottom line with phosphoric is that what it does depends on how much calcium is present. If calcium is at low enough concentration then each mole of phosphoric acid yields about 1 mole of protons in acidifying to a pH near 5.6. This would be the case if you wanted to use phosphoric to, for example, acidify sparge water at pH 7 with alkalinity of 127 due to calcium bicarbonate (calcium concentration 50 mg/L) to pH 5.6. This would require 196 mg/L H3PO4 and with that much added the pH would go to 5.6 because the saturation pH is 5.7 for that level of calcium and phosphate. OTOH if the water had alkalinity 252 balanced by calcium (100 mg/L) it would, ostensibly, take twice as much H3PO4 to reach pH 5.6 but the saturation pH for such a dose would be 5.91 so that the water would be super saturated WRT apatite. IOW the target pH would be reached with less than 2*196 mg/L because saturation would be reached before that amount could be added. When saturation is reached precipitation occurs and in that process each mole of phosphoric acid releases 3 - 2/3 mole of protons. It should be clear that things are pretty complicated with phosphoric unless calcium levels are pretty low.

I have used water high in calcium and precipitated it all to sludge on the bottom of the HLT with phos. I just put in about 5ml of 10% solution and the bottom dropped out.

ajdelange said:

It should be clear that things are pretty complicated with phosphoric unless calcium levels are pretty low.

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I think I'm getting somewhere, as I think I actually understand that!

Now, another question (of course)- can you define "pretty low" for the calcium level? For example, my Ca is 57 ppm while my CaC03 is 207 and pH of 8.2 out of the tap. That seems "low"ish according to your explanation I believe.

Yes, I'd say that's low. Plus keep in mind Kai's observations. They are doubtless empirical but it is often the case that lots and lots of hairy analysis results in but minor refinement to a much simpler model that works in many if not most cases.

What is your target for sparge water? I'm assuming you don't want to go too low because the mash is already somewhat acidic and has decent buffering capabilities?

Hermit said:

What is your target for sparge water? I'm assuming you don't want to go too low because the mash is already somewhat acidic and has decent buffering capabilities?

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I want to keep the sparge below a pH of 6 by the end of the sparge. That's my goal.

I adjust the pH of my mash water and sparge water separately. I have high carbonates and precipitate them overnight with pickling lime (~3 gm in 10 gal) in my boil kettle. Then next day I pump the water into my mash tun and HLT leaving the precipitated carbonates behind. Then I adjust their pH to just under 6.0 with phosphoric acid. I brew lots of pale beers and experience has shown me that when I then mash in, the mash pH is in the desired range (~5.4). When I do a dark beer I leave the pH a bit higher.

FWIW I haven't seen anything in the spreadsheet that would stop it from working in Open Office. There are a couple of minor cosmetic issues between the two versions, but the spreadsheet seems to have everything in it and work fine on several OO installations I've used it on.

Can you describe the problem with the spreadsheet in Open Office? Maybe I can find a way to correct it.

Sounds like your water profile is actually very close to mine. I found it took a LOT of phosphoric acid (like 1/4 of a bottle) to neutralize the alkalinity, due to the high calcium levels, so I have switched to a 85% phosphoric acid (purchased from Duda Diesel cheap) which I dilute to 25%. This lets me add a manageable amount without breaking the bank at $3 a bottle from the LHBS.

For sparge, I use RO water acidified to pH of 5.7 or so with phosphoric acid using my pH meter. I have quit using lactic acid for anything other than tartening up my berliner weiss which isn't quite sour enough out of the fermenter, the amounts I needed to get a correct mash pH were detectable in the brew.

more info for later without a search. Thanks all

How about citric acid? Only 2/3 of a mole of citric acid is needed to neutralize a mole of carbonate. Is there off flavors associated with citric?

Less than that. Whereas it would take 0.72 mmol of phosphoric acid to take 1 mmol of bicarbonate from pH 8.3 to pH 5.9 or 0.76 of lactic it would only take 0.34 of citric.

Yes, citric does have a flavor (and you know what it is like from oranges, lemons etc) but it was found in almost every home brewing recipe, including stouts, at one time. It's dirt cheap (as it is still used commonly in wine making) so I'd suggest getting some and experimenting with it i.e. can you get to the pH you like without excessive flavor contribution.

So how about just using Starsan for phosphoric acid? Starsan is just Phosphoric acid and Dodecylbenzenesulfonic acid and is food safe. Is there any negative effects with dodecylbenzenesulfonic acid?
I've actually used it in the mash once when my PH was slightly high and I left my Lactic acid at my friends house. I have a spray bottle of diluted starsan and just gave the mash a squirt or two.

Saccharomyces said:

Sounds like your water profile is actually very close to mine. I found it took a LOT of phosphoric acid (like 1/4 of a bottle) to neutralize the alkalinity, due to the high calcium levels, so I have switched to a 85% phosphoric acid (purchased from Duda Diesel cheap) which I dilute to 25%. This lets me add a manageable amount without breaking the bank at $3 a bottle from the LHBS.

For sparge, I use RO water acidified to pH of 5.7 or so with phosphoric acid using my pH meter. I have quit using lactic acid for anything other than tartening up my berliner weiss which isn't quite sour enough out of the fermenter, the amounts I needed to get a correct mash pH were detectable in the brew.

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You know, at first I thought phosphoric acid was cheaper. But then I realized that for this last 6.5 gallon batch would require 20 ml of phosphoric acid for 6 gallons of sparge water! And that's being conservative. I typically use 6ml of lactic acid in the same amount of sparge water.

I haven't noticed any flavor contribution from lactic acid in the sparge water with a little sauermaltz in the mash. But I wanted to compare the differences. If I like the results, I think I'll either have to get the "other" phosphoric acid, or consider preboiling my water (or using pickling lime like pjj2a said) and racking off the precipitates.

acefaser said:

So how about just using Starsan for phosphoric acid? Starsan is just Phosphoric acid and Dodecylbenzenesulfonic acid and is food safe. Is there any negative effects with dodecylbenzenesulfonic acid?
I've actually used it in the mash once when my PH was slightly high and I left my Lactic acid at my friends house. I have a spray bottle of diluted starsan and just gave the mash a squirt or two.

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I have no idea- but Star-san would be a very expensive sub!

The other problem with using StarSan as your acid is that we don't know the strength of the acid. A program like Bru'n Water requires the input of the acid strength (%, normality, or molarity) in order to predict how much you should be adding to your water. You're left with trial and error as your only way of figuring out the StarSan addition.

Lorena, I'm assuming you're using a 10% phosphoric acid. I like Duda Diesel's 75% phosphoric. That 6 ml lactic addition is similar to what I had to use when I was in Tallahassee. I thought my beer flavor was unaffected by the lactic in that case.

mabrungard said:

Lorena, I'm assuming you're using a 10% phosphoric acid. I like Duda Diesel's 75% phosphoric. That 6 ml lactic addition is similar to what I had to use when I was in Tallahassee. I thought my beer flavor was unaffected by the lactic in that case.

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I am using the 10%. When I brewed early in the week, I used your spreadsheet to calculate the amount of the 10% phosphoric and with my tap water, I would need around 35 ml, if memory serves. I had a mix of RO, though, and that calculated to a 20 ml addition. That's what I did.

I used phosphoric for the first time this weekend. Brun says I needed 22 ml for the sparge... Wow. It was 32 ml total.

That's a few brews per bottle!

I'm going to look into that 75% stuff. If it doesn't break down in storage, I'll mix it down to 25% also and keep it in the 10% bottle!

I don't plan on using Citric Acid, but considering you use such a very tiny amount, couldn't you measure, say 2 grams and make a solution with a precise amount of distilled water, say 12 ounces? Then you wouldn't have to be as precise when measuring the liquid.


EDIT: According to the Duda Diesel's website, that phosphoric acid is actually 85%.

mabrungard said:

Lorena, I had poor impressions of OpenOffice also. I've been much more impressed with LibreOffice. Its almost like using real Excel. Bru'n Water should work well for you there.

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I had trouble with Bru'n Water and OpenOffice at first, but I discovered that I could save Bru'n Water as an .ODS file before I entered any data and started using it and it worked just fine.