Partial Mash water chemistry

[Sublime8365]

So I've decided that I would like to brew more often but seeing as there's only so much beer I can drink I've decided to do alternating full (5.5 gal) and half (3 gal) batches. I've also decided to do partial mash for the half batches to try to shorten my brew day time.

Anyway, I've never actually done partial mash (skipped right from extract to all grain long ago). I've only recently (last 5 or so batches) started getting into altering my water chemistry rather than relying on tap water.

Does anyone have any philosophy on partial mash water calculations? I've read that the extract would have the necessary minerals and if you're doing extract brews that RO water would suffice without any additions but I'm not sure how this works with partial mash.

Would I want to make additions to the mash based on a target water profile for the style, do the same with an appropriate amount of sparge water, then use RO to get to my pre-boil volume? (I'll be doing a full boil but wouldn't need all that volume for mashing and sparging of the grains).

 

[Hermit]

I would think if you are doing a partial you still want to hit the target pH. You just won't pay as large a penalty for missing it. You are still mashing.

 

[Sublime8365]

Yeah I'll certainly look to hit my mash pH, but what about calcium, chloride, sulfate, etc additions? Can I rely on the extract to provide all of those in the finished beer? Probably not.

Let's say that my final beer is 50% extract and 50% grain. Would the recommendation be to essentially treat the mash and sparge as if I was shooting for a batch half the size of my final desired volume? So make my gypsum, etc additions as if I were making a beer just from the grains in my partial mash, which would yield half of the volume I'm shooting for, then add the remaining half of the pre-boil water as RO water with no additions and let the extract make up for the rest of the minerals?

 

[Weezy]

You could treat the mini mash part like a separate beer with separate water profile. But i'd recommend just using all RO for the first time and seeing how it turns out before you try mineral additions. When I do them, I do add 1/2 gram/gallon of gypsum to RO for IPAs. For other beer styles, I add nothing.

Also, and I should put this in my sig since I seem to day it so much, I believe people who say they can taste 'extract twang' are using tap water with extract and ending up with a heavy mineral profile.

 

[Hermit]

The extract supplies the bulk of the profile and you don't know what that was. You would have to see if you can get that information from the extract maker. They probably have a 'decent' water profile since they are doing this in bulk but you simply don't know. I think Weezy has the right idea.

 

[GotPushrods]

The extract supplies the bulk of the profile and you don't know what that was. You would have to see if you can get that information from the extract maker. They probably have a 'decent' water profile since they are doing this in bulk but you simply don't know. I think Weezy has the right idea.

I've asked several extract producers several times. I always get the "it's proprietary information" line. If someone manages to squeeze some info out of them, feel free to post it here. I'd love to know as well.

 

[Sublime8365]

Thanks guys, I'll likely stick with something close to 100% RO water. I'm doing a stout so I might add some calcium chloride to accentuate the maltiness and stay away from the gypsum and hope the extract provides the rest.

 

[TheHappyHopper]

Sorry to bring up an 8 month old post, but I have some follow up questions on this same topic.

I do partial mash batches and all of the stuff I read about minerals and pH balance, etc., seems to only be concerned with the mash itself. What about my top-off water at the end? If I make sure that my water profile and pH is perfect during the mash, does it matter if I just top it off with tap water, or do I need to top off with the same water profile that I used in my mash?

Also, and I should put this in my sig since I seem to day it so much, I believe people who say they can taste 'extract twang' are using tap water with extract and ending up with a heavy mineral profile.

I wish I had read this 6 months ago - I actually went from 5 gallon all grain batches to partial mash because it was easier for me in my small kitchen. The first couple seemed to turn out pretty good, but the last couple beers (that were lighter), definitely had a harsh flavor which I narrowed down to the minerals in the water, but I never considered minerals already present in the extract...