Correcting mash pH, based on Brun' Water data

I recently brewed a beer, using water with a known alkalinity and total hardness (both quite high).
I estimated additions (acid) to get the pH in range, taking in consideration alkalinity at target pH, the acid dissociation constants and the acid contributed by the malts according to Brun' Water knowledge page.

The a wort sample was taken from the tun 10 minutes after dough-in and the pH measured a few minutes later once the sample was cool.
The reading showed +0.2 from predicted.

I understand that the predictions are based on a model which may not fit well the grain bill and, admittedly despite knowing the total hardness of the water +/- 9 ppm, I do not know for sure the Ca/Mg split.

The question here is, can I use the data provided by the model to decide how on-the-fly additions to correct the pH?

For example, given a water/grist model, for a target pH 5.4 X amount of acid is specified, while for a target of 5.6 X+D amount of acid is specified.
So, if I target 5.4, but get 5.6 after dough in, can I approximate my original target by adding D amount of acid?

thank you

Anyone willing to risk an answer or share personal experience to help the newbie?

p_p said:

Anyone willing to risk an answer or share personal experience to help the newbie?

Click to expand...

I'd use BrunWater for that too.

Use the spreadsheet to figure out how much acid (or acid malt) to use to drop the pH down 0.1 units - like from 5.4 to 5.3. If your mash comes in at 5.5, dump the estimated amount of acid in and give it a good stir. If instead it comes in at 5.6, double the amount and dump that in.

Or, just make a note of the pH and correct next time you brew. That's what I do - just fix it next time and go with what you have this time.

Cheers!

You could try acid malt. I had a difficult time hitting ph with lactic, so I tried acid malt and have hit target every time using Bru n water.

Also, have you tried taken a reading a bit later in the mash? Say, 15-20 minutes?

Dosing with lactic acid is ALWAYS more accurate than using acid malt. Cyan, you are only lucky. Acid malt is a natural product and it can vary and more importantly, the strength of acid malt can vary substantially between maltsters.

Interesting, well for one reason or another I've been very successful with it.

Cheers for the replies

p_p said:

The reading showed +0.2 from predicted.
<snip>
can I use the data provided by the model to decide how on-the-fly additions to correct the pH?

Click to expand...

Your ability to adjust is limited by the resolution of your pH measurements.

If you're pH meter (assuming you have one) is accurate to +/-0.2, then your measurement may have been spot on because it was within the allowed variance of the meter. In the other direction, your mash could have been high by 0.4 pH and still be within the tolerance of most meters used by homebrewers.

To make the precision adjustment you proposed, you'd need a meter that's accurate to +/-0.02.

brewfun said:

Your ability to adjust is limited by the resolution of your pH measurements.

If you're pH meter (assuming you have one) is accurate to +/-0.2, then your measurement may have been spot on because it was within the allowed variance of the meter. In the other direction, your mash could have been high by 0.4 pH and still be within the tolerance of most meters used by homebrewers.

To make the precision adjustment you proposed, you'd need a meter that's accurate to +/-0.02.

Click to expand...

You are right .. My pH meter is +/- 0.1 so my measurement may not be accurate enough to attempt adjusting. I did my best to calibrate it prior taking the readings though, but a cheap meter will always be a cheap meter.

I am just trying to understand if the prediction itself was correct. I am not sure which assumptions have been made in relation to the malt buffers in the water calculators I've used.

I have now been playing with the spreadsheet linked in this thread: https://www.homebrewtalk.com/showthread.php?t=477058

Using some of the data already there to approximate the recipe I brew, the numbers came closer ei. predicted pH 5.54.

Why do I worry about this: well, I like to worry about these things. Plus, I if I feed back to the calculator a slightly more accurate number for the buffer capacity of the grist, next time I brew this or similar recipe I should come closer ... or maybe not