Author Topic: Adjusting pH of Sparge Water  (Read 1854 times)

Offline mister2

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Adjusting pH of Sparge Water
« on: May 26, 2020, 03:57:51 PM »
Measuring and adjusting the pH of my sparge water continues to be the single most painful part of my brew day.  I am hoping someone can point out what I?m doing wrong.  Oddly, measuring and adjusting mash pH has not been a problem.  I must be the only person on the planet having this problem, so I am hoping the fix is easy.  Here is my setup and routine:

Equipment: Electric Brewery controller with three 30-gallon Blichmann tanks
pH Meter: Milwaukee MW 102 with separate, replaceable temp and pH probes
The pH probe is less than 1 year old and has been used for 8 brew sessions.  Calibrating and storage solutions are fresh.  The meter itself is about 2 years old and has been handled very gently.  The temp probe has never been replaced.

Two days before brewing I calibrate the meter using new Milwaukee calibration solution, using one packet each of 7.01 and 4.01 solution.  I always store the pH probe in Milwaukee MA9015 storage solution.  Manufacturer procedures are followed exactly.  Calibrating and storage solutions are less than 1 year old.

On brew day when it is time to measure my sparge water pH, usually during the mash-out, I take the probe from the storage solution for use.  I prepare a small ice bath and use a shot glass to take small sample, about 1/2 ounce, enough to sufficiently submerge the pH probe.  The sample is chilled until the temp probe shows 20?C/68?F and the shot glass is removed from the ice bath.  I then put the pH probe into the sample, keeping the temp probe in it too and wait until the unit locks in (flashing hour glass goes away).  That?s it.  Now for the odd part.  My readings may be all over the place.  For example:

Initial reading of untreated water: 6.10
Add 10 drops of lactic acid; wait 3 minutes while sparge water is recirculated from tank spigot back over top of tank.  Resulting in pH of 6.31.  How is it possible for the pH to go UP after adding acid?
Add 10 drops of lactic acid; wait 3 minutes to mix in as above.  Resulting in pH of 6.11.  OK, not unexpected.
Add 10 drops of lactic acid; wait 3 minutes to mix in as above.  Resulting in pH of 4.92???  Now I?m stumped.

The volume of sparge water I?m adjusting is 17 gallons and is at 170?F.  I have had similar results with more than one pH probe and differing volumes of sparge water, so I?m thinking the problem lies in my procedure.  Questions I have are:

How long should I wait after adding lactic acid when I can re-measure?  My pump is the March nano-brewery which easily recirculates my sparge tank in a matter of minutes.  Manually mixing doesn?t seem to make a difference.  Should I agitate the pH probe while measuring the sample?  I?ve tried both ways.  For completeness, my target sparge water pH is 5.6 to 5.8, and the water has been treated the night before with campden to remove chlorine, completely crushed and mixed in.

Thanks for whatever guidance you can pass along.

Online Oginme

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Re: Adjusting pH of Sparge Water
« Reply #1 on: May 26, 2020, 06:15:09 PM »
I would bet that it is a sampling/mixing issue.  Next time, instead of waiting until mash out to adjust your sparge water pH, I would start once you have started the mash.  Your target should be to bring the pH of the sparge water down below a pH of 6.0, there is really no need to bring it all the way down to your mash target. 

Which leads to the next question, do you really need to adjust the pH of the sparge water?   What is your residual alkalinity?  Are you batch sparging or fly sparging?  If you residual alkalinity is reasonably low, then the pH of the wort will be determined more by the extracted sugar and minerals from the grains rather than your base water. Since the starting pH of your water is already in the 6's, I cannot imagine that you have a very high residual alkalinity which means that the water will quickly equilibrate to whatever extract from the grains will bring it down to. 

If you do want to bring your mash pH down, then you just noted the mixing conditions you need to follow before making any additional changes.  You got no change (basically) at 3 minutes, no or barely a change at 6 minutes, and saw a big change at 9 minutes.  This would indicate that you need to wait somewhat higher than 6 minutes before taking a reading, and closer to 9 minutes would be better.  I realize this does not account for your time in taking, cooling and reading the sample, but you can work that into the dead time to allow your water to equilibrate with the acid addition.
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Offline mister2

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Re: Adjusting pH of Sparge Water
« Reply #2 on: May 27, 2020, 07:23:32 AM »
My reasoning to bring my sparge water to the 5.6 - 5.8 range is strictly on the recommendation of Kal at theelectricbrewery.com, but I will consider that as just one source.  I have made several beers without adjusting my sparge water and think they all came out just fine.  By adjusting my sparge water I am hoping to improve the final product even if it is just slightly.  At this point, it is a mission of mine to conquer this seemingly simple step.  Your recommendation to adjust earlier in the process is a good one since I have more time to let additions mix in.  I'm not sure what my residual alkalinity is, but I'll do some research on how to determine that.  I've heard Palmer speak of it but haven't paid much attention.  Shame on me.  I'm lucky the water in my area has been consistently of high quality and needs no treatment to make really good beer.  I do fly sparge and will probably continue to do so, mainly out of habit.  I am pleased to hear there aren't any obvious problems with my process other than not giving it enough time.  That is one thing I will experiment with without having to wait for a brew day.  Simple is good.  Thanks a million for the info.  Looks like I need to read Palmer's chapter on water.

I would be interested to hear from folks who make larger batches (>10 gallons) as to their methods for adjusting sparge water.  How long do they wait after making additions before remeasuring, etc.?
« Last Edit: May 28, 2020, 01:50:18 PM by mister2 »

Online Oginme

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Re: Adjusting pH of Sparge Water
« Reply #3 on: May 27, 2020, 11:25:46 AM »
Actually, the range of 5.6 to 5.8 is his recommendation for preferred target.  He says you just need to get your sparge water below 6.0 not unlike what I stated above.

Your actual target is really dependent upon your water mineral and ionic make-up.  I would highly recommend getting your water tested for the key ions as listed in the water profile: Calcium, Magnesium, Sulfate, Chloride, Sodium, Bicarbonate.  Kal has a nice description of adjusting your water and uses a similar approach to defining basic flavor profiles that I prefer.  This can potentially get you a lot farther in improving the outcome of your beer than just controlling the wort pH. 

Just one additional word of advice:  It does not matter what other people do in their process when it comes to timing of acids and mineral salt additions.  Their process may be a lot different from yours and respond much faster or slower than yours is apparently reacting.  Understand why they do it, but transfer only the thinking behind the timing they use and not the nuts and bolts of what they do.
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Offline mister2

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Re: Adjusting pH of Sparge Water
« Reply #4 on: May 29, 2020, 10:52:03 AM »
Actually, the range of 5.6 to 5.8 is his recommendation for preferred target.  He says you just need to get your sparge water below 6.0 not unlike what I stated above.

This is precisely why I chose the range of 5.6 to 5.8.  We are saying the same thing.  Regardless of the target value, my main concern is with taking an accurate measurement at the right time.

I have experimented by measuring the pH of 17 gallons of water after adding 20 drops of 88% lactic acid.  I took a sample every 2 minutes, cooled to 20?C and then measured the pH for 30 minutes.  It took 16 minutes for the readings to equalize.  My pump was recirculating the water the entire time at a rate of approximately 5 gallons per minute and I did not do any additional manual mixing.  I now have a better idea of how long it will take the pH to equalize with this volume of water.  I may experiment more with larger volumes.  I have never read from others advising to wait 15+ minutes after making acid additions, but that was certainly my case.  I would assume it takes less time for smaller volumes to equalize, but I would still like to hear from others who adjust 20-30 gallons.
« Last Edit: May 29, 2020, 01:57:13 PM by mister2 »

 

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