Bru'n water wrong for no sparge?

I am doing my first no sparge today. Mashing in my 10 gallon cooler with 8.4 gallons water and about 10 pounds of grain. It's an English ale that is golden promise with about 11% 30L crystal, 3% 85L crystal, 3% 350L chocolate.

Bru'n water had me add 4 oz of Acid Malt to get the pH of 5.4 (my water is very soft). It seemed a bit much. Anyways my actual mash pH ended up being 5.08.

Has anyone else had this issue? I am guessing it is the huge amount of mash water that is the difference. I've never had any other issue with Bru'n water. I've made light beers, dark beers, whatever, and Bru'n water has always been within 0.1 pH of my measured.

You used the proper amount of water for the batch size, where you show the mash pH and water profile? You put in the amount of water in the mash, and the amount for the sparge (in this case 0), and then the batch size?

Yes. I've checked everything over and over again making sure I didn't mess anything up. Here are screen sheets from the spreadsheet...

http://imgur.com/a/4265P

The pH meter is new, so the buffers are new too. I've used the meter and buffers for about 6 brew since I bought it in November. It calibrated just fine today like it has every time with a slope of 97%.

My crushed grain bucket had more powdery stuff than usual from my last brew. Maybe that had some lactic in it? I thought about it briefly before I crushed. But there is always some stuff left over in it. I don't really clean it out each time.

You can't expect to get a very good mash pH prediction when all you tell a calculator is that the base malt is 'base malt' of a particular color. They differ quite a bit. If I put your particulars into a mash pH prediction spreadsheet it estimates a mash pH of 5.28 if I tell it the base malt is Weyermann's pneumatic pils, 5.35 if I tell it the base malt is Weyermann's floor pils, 5.34 for Crisp's Maris Otter and 5.46 for Munton's Maris Otter. My guess is that your base malt has an unusually low DI mash pH (around 5.52) and/or low buffering capacity (-30 mEq/kg•pH) but it is only a guess that would explain your observed 5.08. Other possibilities are unusually acidic colored malts or sauermalz or a combination of all of these factors.

You really should not rely on spreadsheets or calculators except to give you broad guidance. You should always check spreadsheet predictions against a test mash. Where you have confidence in a spreadsheet based on experience with a particular brew it is a fine tool for calculating, for example, how much an addition of another couple of oz of chocolate malt will drop mash pH but when going to new materials one can certainly expect discrepancies of the magnitude discussed here.

I have had it happen once or twice and my pH was closer to a 4.8 at mash temp. All I could think was either I had too much acid malt, my water supply changed that week, or the acid malt was somehow MORE acidic. I believe my brew was okay overall and I hit my gravities but I'm here to say I have had it happen and it seems to be rare.

Ok thanks so much for the responses. A lot was new about this batch. Never used golden promise, new batch of acid malt, never used Carastan (let alone a pound if it!). So sounds like it is probably not the full volume mash.

I'd like to think acid malt would be fairly consistent from lot to lot. Otherwise maybe I should switch to acid additions.

In this case, I ended up adding baking soda to increase pH but ended up over shooting a bit so my end of mash was about 5.44 and end of boil was 5.38.

Was correcting the pH the right response? I was about 30 minutes into mash and conversion had already occurred anyways.

There's a thread https://www.homebrewtalk.com/showthread.php?t=387040 where Martin Brungard and Kaiser discuss limitations of the calculators with thin mashes. (See posts 5 & 10 in particular.) It makes me wonder if the calculators just aren't good for pH of a no sparge mash.

I did 12.5 lbs of golden promise, .25 lb acid malt, 8 oz gypsum and 4 oz CaCl in 4gallons mash and 4 gallons strike and I believe I was around 5.2-4 using a test strip.

DurtyChemist said:

8 oz gypsum and 4 oz CaCl

Click to expand...

Shall we assume grams, not ounces? Half pound of gypsum seems a touch on the heavy side.

Quaker said:

Shall we assume grams, not ounces? Half pound of gypsum seems a touch on the heavy side.

Click to expand...

wow. I even SAID ounces when i typed it. Yeah grams.

That's a great thread. Short but exactly what I was looking for. I guess in reality I'll just have to see. As I do more batches with no sparge or sparge.

My gut tells me the full volume mash played the biggest difference. If the recipe is good maybe I'll try it again with a regular mash as see what that does.