Author Topic: Water treatment for reiterated mash  (Read 378 times)

Offline jc24

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Water treatment for reiterated mash
« on: April 25, 2018, 11:41:42 AM »
Hoping Martin will chime in here...

I will be brewing a fairly standard RIS soon, but, due to the limitations of my system (Grainfather), I'll have to do a reiterated mash, but I'm wondering how best to treat my water for each step? I start with 100% RO water. My plan is this - keen to hear thoughts/suggestions (and yes, I know I could just add extract and do one mash, but I want to give this a go!):

1. Mash exactly half the grain bill as per usual at 149°F for 60mins, treating the water as per usual for that volume (in this case it will be 4.6 gallons) but leave out the Gypsum and CaCl2 additions as I'll be needing to raise the RA of the mash.

2. Sparge the first mash with pure RO water to reach full pre-boil volume.

3. Pump off wort into a separate vessel that I'll use for the 2nd sparge, until I'm left with 4.6 gallons of wort in the mash tun for the 2nd mash.

4. Add the 2nd half of the grain bill, mash at 149 for 120mins.

5. Sparge using the wort collected in step 3 above.

6. Add Gypsum and CaCl2 additions and boil as usual.


Offline mabrungard

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Re: Water treatment for reiterated mash
« Reply #1 on: April 25, 2018, 11:55:33 AM »
I guess that's one way to do it. I can see that the efficiency will be a little lower due to using wort as your final 'sparging' liquid.

While I understand your withholding the mineral additions from the mash to help keep the RA and resulting wort pH up, you are only delaying the inevitable. Most stouts and porters benefit with a softer and fuller roast character when the kettle wort pH is kept a bit higher than other styles, say 5.4 to 5.6. When you add those reserved minerals to the kettle, the same reaction still occurs in the kettle and wort pH will drop. You are better off boosting alkalinity as needed to produce the proper mashing pH and then have that carry over into the kettle.
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Offline jc24

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Re: Water treatment for reiterated mash
« Reply #2 on: April 25, 2018, 12:41:13 PM »
Thanks for the quick reply. OK I think I'll forget about sparging with wort, and sparge with water as normal. I'll also add the Gypsum at the start. So it will now look like this:

1. Mash half the grain bill as per usual at 149°F for 60mins, treating the water as per usual for that volume (in this case it will be 4.6 gallons).

2. Sparge the first mash with enough treated RO water to reach 4.6G of wort, ready for the 2nd mash.

3. Add the 2nd half of the grain bill, mash at 149 for 120mins.

4. Sparge with treated RO water to reach full pre-boil volume.

By the way, here is my estimated profile - Ca seems a little high (I'm using Pickling Lime to raise RA), but I'm thinking it should be OK?

Estimated Profile
Ca = 157
Mg = 6
Na = 36
SO4 = 36
Cl = 46
Bicarbonate = 477

Estimated mash pH: 5.51

Offline mabrungard

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Re: Water treatment for reiterated mash
« Reply #3 on: April 25, 2018, 04:32:09 PM »
The 477 ppm bicarb seems a bit high, but I'm guessing this is a high gravity wort.

Assuming you are working with the free version of Bru'n Water, the actual ion concentrations will be lower than the mashing concentrations that I think you're showing. That should help alleviate the concerns with Ca and HC03
Martin B
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Offline f00b4r

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Re: Water treatment for reiterated mash
« Reply #4 on: April 25, 2018, 06:06:29 PM »
Best in mind that you may also be able to split the two grain bills into the initial one containing all the dark malts etc and the second one with just base malts in (dependant upon your grist).

Offline jc24

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Re: Water treatment for reiterated mash
« Reply #5 on: April 25, 2018, 10:55:38 PM »
The 477 ppm bicarb seems a bit high, but I'm guessing this is a high gravity wort.

Assuming you are working with the free version of Bru'n Water, the actual ion concentrations will be lower than the mashing concentrations that I think you're showing. That should help alleviate the concerns with Ca and HC03
Yes I’m using Bru’n Water and yes to the high gravity - OG = 1.100, 2.2lbs each of Roasted Barley and Chocolate Malt so yep, high bicarb!


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Offline jc24

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Re: Water treatment for reiterated mash
« Reply #6 on: April 25, 2018, 11:00:25 PM »
Best in mind that you may also be able to split the two grain bills into the initial one containing all the dark malts etc and the second one with just base malts in (dependant upon your grist).
I’m tempted with this but with 2.2lbs specialty malt, I’m wondering if my yield from mash 1 would be too low if I added it all at the start? Total grain bill is:
14.1lbs Maris Otter
1.9lbs Malted Wheat
2.2lbs Roasted Barley
2.2lbs Chocolate Malt
0.7lbd Crystal 120


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