Increasingly mash alkalinity from RO (for Weizenbock)

[Barley_Bob]

I recently started brewing from RO water, and I'm having some trouble. I am using Bru'n water, but solutions are elusive. I'm brewing a weizenbock tomorrow, and my mash pH is coming up way too acidic. I don't often brew darker colored beers, and this is my first using RO, so I need some experience.

I've tried removing the 4oz of roast malt, 8oz of crystal, and 8oz of aromatic I'm using from the mash (to instead steep), and I've even added a gram of baking soda and removed my sulfate and chloride contributions (to add to the boil). All of that manages to get me a mash pH of 4.9. I don't want to use a lot of baking soda (for obvious reasons), so I'm not sure what to do. Pickling lime is apparently an option, but in my research into other posts, Martin has cautioned against it unless you have an amazing scale, which I do not (mine is digital and rounds to the nearest gram). Also, I don't have any pickling lime. The real problem appears to be the 10lbs of German Wheat malt, which is making an acidity contribution of 5.9. My other malts make a negligible contribution.

I could also cut the RO with some of my tap water, but the results are going to be extremely unpredictable. My tap is extremely hard, is run through a softener, and I certainly have not had it tested. So, this is an option, but I think it's a poor one.

I'll really appreciate any help, and I'm looking forward to hearing from someone. Thanks!

 

[JonM]

What's your mash thickness? A thinner mash might help.

 

[Singletrack]

I like the idea of blending RO with tap water. This may have value in providing some trace minerals too. However, pull the tap water prior to softening. You may be able to get your water company's water quality report on line. This will provide an estimate of the mineral concentrations for blending.

I always blend like this, and I have had good results, for what that's worth.

 

[Walrus1228]

I agree. Three points:

Thinner mash, BIAB? A little bit of baking soda makes a big difference. And 4.9 is good enough, especially if mash is hot when measured.

 

[JonM]

Can you post a screenshot of your bru'n water calcs?

 

[Barley_Bob]

Thanks for the quick responses guys!

My mash thickness is 1.25 (qts/lb). If I up it to 1.75, the pH jumps to 5.2. Is that an acceptable ratio? I usually shoot for 1.25, but I do have space in my mash tun for this.

Blending with my tap is an option, and I could get the unsoftened out of my hose, I think. If I jump that ratio up to 1.75, I could use 5 gal of RO and 2 of tap. I'll end up using some tap as top off water anyway, so it's not like I'm totally against it... Maybe that would be enough to get me from 5.2 to 5.4?

100% dilution (that got cut off).

 

[Barley_Bob]

I have pH strips, but they're the ones that test from 1-9pH, so they're not super duper reliable.

 

[doug293cz]

I have pH strips, but they're the ones that test from 1-9pH, so they're not super duper reliable.

Those are useless for brewing. The only pH strips that are marginally acceptable are the ColorpHast strips with the pH 4 to 7 range, and they are EXPENSIVE. Even the ColorpHast strips only claim 0.2 - 0.3 pH accuracy; not really good enough.

Brew on

 

[JonM]

Are you sure that German wheat is supposed to be 40 Lovibond? Most wheat is in the 2-3 L range. Best Dark Wheat is 7.3 L. I gave a look through the chart in Malt, and nothing comes close to 40L.

I'd double and triple check that, because I think that's your error.

 

[Barley_Bob]

Nice save, Buddy! I haven't been able to brew as much since I took a new job, and it's been a while since I've used Bru'n water. I kind of forgot that it doesn't autopopulate default values for malts. Woops. The German wheat is 2.5L, haha. A little bit different. With all my malts in, along with a gram each of gypsum and calcium chloride, my mash is right on the money.