Grainfather + Bru'N Water = Mash pH Off

[TheHopfather]

I recently picked up a Grainfather and quickly knocked off 2 batches with it. With both of these batches I ended up with my mash pH being pretty far off from what Bru'N Water predicted (0.27pH & 0.21pH respectively). Not sure why this is happening...

I used to BIAB on my stove top, I use 100% RO water and build my profiles in Bru'N Water using salts and 88% lactic acid. My BIAB batches were always pretty spot on in regards to pH, suddenly, with the new machine, the calculation is off.

The first recipe I did was a simple pilsner - 9.6lbs pilsner malt & 0.4lbs Munich. The Grainfather water formula called for 4.16 gal mash water, Bru'N Water wanted 2.1g gypsum & 1.8g calcium chloride along with 1.9mL of lactic acid. This was for a predicted mash pH of 5.30, measured mash pH ended up being 5.57 (15 min into the mash, measured at 20C).

I thought this was a one off and didn't worry about it too much. However I put a second batch through the machine last night and had a similar result on that one as well. Predicted pH of 5.30 and a measured pH of 5.51. Does anyone have any insight as to why Bru'N Water is seemingly having trouble predicting mash pH on this machine?

 

[Kampenken]

Hmm, that's odd to me, I use a GF & Bru'n Water too, but don't have a meter to check my pH - I've read lots of good reports on Bru'n Water's estimate accuracy so didn't feel the need to "double check". What I don't understand is how target pH would be different whether "regular" BIAB v GF. I expect the pH is moved by starting water profile, grain additions, amount of water and your water adjustments, and have nothing to do with system. Maybe reach out to Martin (of Bru'n Water)?

 

[normonster]

No insight but I've noticed that it tends to overshoot my acid additions. I have adopted the practice of adding only half what is recommended, testing with meter, then adding drop at a time from there. I'm 3vessel if that matters.

Very strange though that you're getting different results between the two systems, though 5.51 from 5.3 is seems pretty close and in the range. At the least, you have room to add another drop of acid and move it down closer to your target.

 

[TheHopfather]

Confused me too. The only real difference between the GF and BIAB would be the water to grist ratio. As I understand it BIAB needs more acid for the full volume mash but Bru'N Water was always spot on, I'm having trouble understanding why it is off with the GF.

I suspected the meter might be the problem but it was reading spot on to my calibration solutions last night. Perhaps my local RO water machine isn't giving me as pure water as it was in the past and I'm dealing with alkalinity I'm not aware of? I don't have a TDS meter to test that theory out with.

 

[mabrungard]

For the resulting pH to be higher than what the program predicts, it probably points to your RO water being not as pure as you expect it to be. If you don't have a TDS meter, you have no way to know what your RO source is giving you. Those TDS meters are cheap. I like the units from HM Digital, but there are plenty of other reputable brands. Don't buy an unbranded cheapy off of Ebay. You'd only save a few dollars.

 

[Kampenken]

For the resulting pH to be higher than what the program predicts, it probably points to your RO water being not as pure as you expect it to be. If you don't have a TDS meter, you have no way to know what your RO source is giving you. Those TDS meters are cheap. I like the units from HM Digital, but there are plenty of other reputable brands. Don't buy an unbranded cheapy off of Ebay. You'd only save a few dollars.

Martin, great to hear from you on this, I was quite interested to hear your opinion, so thanks for chiming in. If you don't mind, I have some questions. I have a water report from my municipality, and rely on that as well, so it too could be off (or even change due to seasons, its reservoir water). So while I rely on your estimates, and am pleased with the beer results, maybe I should consider measuring? If so, what tool would you recommend to test the tap water, and what pH meter?

Thanks!
Ken

 

[mabrungard]

If there are doubts regarding the composition of your tap water, using aquarium test kits for alkalinity and calcium content are great checks. Their concentrations have the greatest impact on mashing pH.

If you are considering a pH meter, I recommend that you read my thoughts on that subject on Bru'n Water's Facebook page. Don' be too cheap.

 

[ajdelange]

The first recipe I did was a simple pilsner - 9.6lbs pilsner malt & 0.4lbs Munich. The Grainfather water formula called for 4.16 gal mash water, Bru'N Water wanted 2.1g gypsum & 1.8g calcium chloride along with 1.9mL of lactic acid. This was for a predicted mash pH of 5.30, measured mash pH ended up being 5.57 (15 min into the mash, measured at 20C).?

5.57 is not an unreasonable mash pH for 1.9 mL of lactic acid with that amount typical pilsner and Munich Malts. Depending on whose Pils and whose Munich is used mash pH estimates vary between 5.50 and 5.69. You would need twice the lactic acid (3.8 mL) to get pH's from 5.4 to 5.59 again depending on whose Pils you are using.

IOW what you are measuring is more or less what is to be expected. The program estimates are off because the programs aren't very good estimators unless they have detailed data on the individual malts and they don't. Weyermann's pneumatic pils malt has a DI mash pH of 6.62. Rahr pils has a DI mash pH of 5.80. Your program needs to be aware of the spreads in base (and other) malt parameters. Most of then just ask for Pils and use some value to characterize all Pils malts. If the program's values match the malt you happen to be using then you get an estimate which matches what you see in the mash tun. Change to a different malt that doesn't match what the program has stored and you are off by a couple of tenths.

The other possibility is that you entered data wrong.

 

[TheHopfather]

Interesting, thanks AJ, I wasn't aware the source of malt would influence pH that much. When I asked in the past my LHBS was using Great Western. At the time Bru'N Water was really close to my meter, close enough that I stopped measuring for a few batches. When I got the Grainfather I decided to bust out the pH meter again. I wonder if the LHBS switched malters on me and I wasn't aware, I'm less than 2 hours from Alix (home of Rahr), along with several other malters.

So it looks like my issue is either my RO machine isn't dispensing as pure water as it was in the past, my LHBS may have switched malt sources on me or user error.

 

[ajdelange]

It's unlikely your RO machine would go TU over night. This seems especially unlikely as your mash pH was just about where it should be given the malts you used. It would, nevertheless, be a good idea to check the RO output with an inexpensive TDS meter.