Why is my mash pH always way off target?

[Cptn_Needa]

I have spent quite a bit of time researching this, and I will let somebody better qualified say:
But none of this matters since by convention pH values in brewing are reported as the pH of a room temperature sample. This arises from the laboratory practice of cooling pH samples before pH is tested. While pH meters can correct for temperature and their probes may be able to withstand higher sample temperatures, testing only cooled sample extends the life of the probe. This common practice also means that reported pH optima and pH ranges are for room temperature samples even though the actual reaction happens at higher temperatures.

Ah Ok. Thanks for the correction.

 

[2Beers]

I think, also, that my ph meter is only rated for 20ish degrees C. Full mash temp is prohibited in the instruction manual. I take a sample and try to cool it down,with limited real-time success.

 

[foxy]

I would be trying my water calculations somewhere else just to see if it gives you the same additions. You could try Bru'n water, get the one where you donate, not the free one and Martin will help you out.

 

[Galena]

I would be trying my water calculations somewhere else just to see if it gives you the same additions. You could try Bru'n water, get the one where you donate, not the free one and Martin will help you out.

Well I have tried the free one as well as Easy Water Calculator and they are both very close to Brewfather

 

[foxy]

Well I have tried the free one as well as Easy Water Calculator and they are both very close to Brewfather

If three calculators come out similar then it must be water report which is cactus. Or the pH meter, lucky to get 18 months life out of a probe.

 

[Galena]

If three calculators come out similar then it must be water report which is cactus. Or the pH meter, lucky to get 18 months life out of a probe.

I'm not sure how you know when a probe has gone? It is never far out when calibrating, and I checked my tap water pH yesterday with it and it was quite close to the Severn Trent monthly report.

 

[foxy]

I'm not sure how you know when a probe has gone? It is never far out when calibrating, and I checked my tap water pH yesterday with it and it was quite close to the Severn Trent monthly report.

When a probe goes it is way off, I was lucky and my Hanna was about 2 years old when the probe carked it, but fortunate to have a Hanna Instruments outlet near me. The probe cost almost as much as the meter. My mash pH is constant now, I know what salts to add so never use my pH meter any more.

 

[Hazelwood Brewery]

Whenever my pH meters are on the way out readings fluctuate all over the place and never settle.

 

[Galena]

Whenever my pH meters are on the way out readings fluctuate all over the place and never settle.

Mine is still quite stable so I guess okay then

 

[Sadfield]

The natural pH of malt is variable from supplier to supplier, season to season. So perhaps the spec of your malt is different to the values the calculator assumes. Mash thickness will also have a bearing, thinner mashes will have a more dilute buffering capacity.

 

[Galena]

The natural pH of malt is variable from supplier to supplier, season to season. So perhaps the spec of your malt is different to the values the calculator assumes. Mash thickness will also have a bearing, thinner mashes will have a more dilute buffering capacity.

True, and I haven't experimented with mash thickness which is probably worth trying, it's just that no matter how much I try and bring the pH down by targeting too low and adding salts and acid to achieve this, my pH refuses to go 5.5

 

[Hazelwood Brewery]

Nothing seems to explain the buffering issue as yet but I understand VWP is basically sodium hydroxide, a strong alkali. What if, similar to my case, silicon hose is “sticky” to sodium hydroxide molecules and a fine layer is retained inside the hose? This would almost certainly cause pH problems, especially when you’re only adding enough calcium for low alkalinity.

 

[Galena]

Nothing seems to explain the buffering issue as yet but I understand VWP is basically sodium hydroxide, a strong alkali. What if, similar to my case, silicon hose is “sticky” to sodium hydroxide molecules and a fine layer is retained inside the hose? This would almost certainly cause pH problems, especially when you’re only adding enough calcium for low alkalinity.

Looking back through my earlier brews (I have only been recirculating with a pump for a very short time, manually recirculating before that) I have always been well above my target. The closest I ever got was 5.36 on a bitter with a target of 5.22 and 5.33 on Czech pilsner with a target of 5.13. An Oatmeal stout was 5.73 an IPA 5.57, the same bitter made again 5.49 and Adnams Broadside at 5.62 and all the rest in the 5.5 area. The beer pH always seems to be in the right range though.

 

[Druncan]

I was having problems with my pen ph meter variations. kept having to re-calibrate with ph4/7. After advice from here I got probe cleaner and storage sols. Sorted!

 

[nickjdavis]

I have spent quite a bit of time researching this, and I will let somebody better qualified say:
But none of this matters since by convention pH values in brewing are reported as the pH of a room temperature sample. This arises from the laboratory practice of cooling pH samples before pH is tested. While pH meters can correct for temperature and their probes may be able to withstand higher sample temperatures, testing only cooled sample extends the life of the probe. This common practice also means that reported pH optima and pH ranges are for room temperature samples even though the actual reaction happens at higher temperatures.

The only bit of this I would clarify is the bit I have highlighted in red. There is a common misconception about what pH meters with Automatic Temperature Compensation (ATC) actually do.

There are two things that variation in temperature cause..

1) the pH of the sample being measured will vary....this is the oft quoted 0.3pH difference between a warm and cool sample
2) a variation in the electrical response of the meter/probe itself

PH meters with ATC correct provide correction for the second of these things, they do not correct for (1)

At the end of the day its easy to get hung up on pH and what the measurement temperature should be...all I would say is that as long as an individuals day to day brew process and measurement regime are the same across all brews then, whatever you measure, will be meaningful in terms of identifying brew to brew variances.

Once your mash is underway, there is very little you can do to affect a change in the pH....by the time youve taken your sample (maybe 10 minutes in to the mash), cooled that sample to 20 degrees, measured the pH, decided what "other" additions you would like to make to the mash to try to adjust the pH...it's actually too late too make any meaningful difference...a lot of the conversion will be complete. Far better that you use the reading to plan for adjustments for the next brew, rather than trying to adjust this brew "on the fly".

 

[Galena]

I was having problems with my pen ph meter variations. kept having to re-calibrate with ph4/7. After advice from here I got probe cleaner and storage sols. Sorted!

I have and use the storage solution, I have not seen a probe cleaner can you show me an example?

 

[Galena]

The only bit of this I would clarify is the bit I have highlighted in red.......

Thank you for your comprehensive reply.
I am aware of the points you make which is why I always measure at room temperature and because of the time this takes I have never tried to further adjust after this point. I agree I probably shouldn't get hung up on it, but I am there has to be a reason that I cannot lower my pH it seems no matter how much salt additions or lactic acid I add.
I am tempted to go a bit crazy and really overdo it to see if it is achievable but hesitate to risk ruining a brew with all the effort that goes in. Having said that you have just given me the idea of experimenting with a small stove top brew and see if I can get the pH where I want it and what it takes to do it.

 

[Galena]

Having done a couple of mini mash's today to test things, I am thinking that perhaps part of the problem is the gypsum not dissolving adequately. Normally I fill the kettle and HLT the night before and add the salts then and giving a stir but having seen today how hard it is to get it to dissolve in a pan with lots of stirring from cold to mash temperature I think maybe its just sitting under the false bottom and not really fully doing it's job. For the next brew I will dissolve the salts in a separate vessel and then add to the brew before heating.