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You are here: Home --> Forum Home --> Brewing Forum --> Brewing Discussion --> pH on Recirculating Mash

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Charter Member
Riverside, CA
313 Posts

Or, you know, enjoy building things.

Posted 34 days ago.

Charter Member
Eden Prairie, MN
301 Posts

@uberg33k - yeah @mchrispen is correct that I am designing and shopping for an e-brewing system. 

But more immediately, I just want to understand how mash chemistry works in fly sparging and whether any of the conditions there apply to recirculated mashes and stepping mah temps through recirculation. Further, to the extent the recirculated mash is not no-sparge, will a recirculated fly sparge avoid pH issues (apparently not). 

I'm especially trying to understand if draining the mash for recirculation removes the buffering agents the mash or creates a gradient, and if so does the recirculation recharge and remix those buffering agents adequately?

In terms of why build and not buy? I haven't ruled out buying, but I haven't ruled out buying but haven't found the system that does exactly what I want. I'm looking for something that's like a cross between the Uni-Brau and the DIY Countertop Brutus 20. I haven't finalized my requirements, but I know it has to be very portable 120V, <=15A system capable of heating strike water on a timer and delivering 3 gallons of wort at knockout, and mashing 10-12 lbs of grain, alarms, and manual pump and current control. I might just design a custom control panel and see if someone will build it for money. 

Posted 34 days ago.

Bastrop, TX
485 Posts

Hey Chino, RE a circulated sparge: this will require some specialized valves that will not create suction on the outlet into the boil kettle. A siphon is created under the mash. If you can manage the pump flow, you can circulate and run-off at a rate that the pressure differential doesn't pull air (or wort) from the BK back into the system. I cannot do this on the Brew-Magic without changing the internal plumbing. As a procedure, it seems counter productive.

Technically, I do not circulate during lautering (continuous fly sparge), save the intial hard pumping step to firm set the mash bed, without run off. This gives me krystal clear run off (if that matters). I don't count this process in my lauter timers.

My typical procedure is to circulate throughout the mash and increase the mash out circulation speed to further compact the mash bed without sticking it, stopping the flow a moment to allow the pressure to equalize, and then slowly draining the mash to the kettle. Think of it as a continuous vorlauf during the mash and mash out. Then, by changing the valve configuration, I pump over from the hot liquor only to the top of the mash the clear sparge liquor, attempting to match the rate of wort flow into the BK with the pump over of sparge water.

In my system, if I do nothing to my RO sparge water (no acid or additional calcium salts), a target 5.4 mash pH will result in approximately a 5.6-5.8 pre-boil pH. If I acidify to 5.4 (usually only a ml or less of 88% lactic in the untreated RO liquor), then the resulting pre-boil pH will be roughly stable at 5.4. With a hard boil on my system, I will see a 0.3 pH unit drop over 60 minutes, with a post-boil pH of roughly 5.0-5.2 (depends on the grist) and yielding excellent break material formation (enhanced by kettle finings in you choose). A fully 90+% efficient lauter will exceed 45 minutes.

If you batch sparge, then the bulk of stabilized pH wort runs into the kettle, leaving a significantly lower mash buffering capability. The sparge infusion will then has a larger potential effect, but since the process is much faster, the buffering reactions are minimized as liquor to mash contact times are dramatically shorter (say 5 minutes vs 45-60 minutes). A larger portion of the sparge liquor ion concentration of will make it into the kettle, with less mash contribution. This should result in a relatively higher pre-boil pH that will stabilize lower as the boil continues.

RE the buffering: If the mash pH is in equilibrium below 7.0, the available buffering capability of the mash and liquor's carbonate/bicarbonate/hydroxide has been exhausted in the entire mash, leaving free acid. So if the mash stabilizes at 5.4, the introduction of 6.0 pH sparge water will cause the overall lauter pH to rise (dependent on the speed of lauter), and should be indicated in the pre-boil pH.

So - batch sparge lautering with pure RO would result in a higher pre-boil pH, but rapidly stabilize and drift to the final post boil pH. A good fly sparge will moderate the pre-boil pH depending on technique and length, but ultimately achieve the final boil pH earlier. The final boil pH should be more or less equivalent between the two.

If you have time to chat this weekend, let's schedule. Easier to answer RIMS questions in real time.

Posted 34 days ago.

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