RO pH way low??

[drkwoods]

I picked up a pH meter and decided to try the Sierra Nevada (Gordon Strong) method of acidifying all brewing water to 5.5pH with phosphoric acid. I didn't even get to open the bottle acid, my first measurement on the RO water was 5.0? What? I immediately re calibrated the meter and retested..5.0 again. Wow. So I brewed with it and the Mash pH drifted between 5.4 and 5.0 on a mostly pils malt Oktoberfest so I was happy with that. I know oxygen can get into the RO water and cause the pH to drop, but 5.0?
Is this a bad pH meter? (I doubt it) or is this not a wild artifact?


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[Roundhouse]

That's weird. I just brewed yesterday with RO water and mine measured at 6.12 ph. Incidentally I always use the Gordon Strong method now. The quality of my beers has gone up noticeably since I started using his method. Water has actually gotten quite easy as a result. I don't see any need for water spreadsheets or calculators. Just a few basic style guidelines and your palate to go by.

 

[drkwoods]

ok, 6.12 is low-ISH but certainly not a 5.0. hmmm. Im gonna get more water this week and measure it again. It did sit over night in the carboy without a top, is that enough to gain oxygen and get a low pH like a 5?
I totally agree with you Roundhouse, that book (BBB) alone has made all my beers better.
I did find this www.puretap.com/ph.htm and it says between 5-6 is common.. wow.. I guess more experimentation is necessary

 

[Roundhouse]

The only time I find his method to be difficult is when brewing my porter. It is 36% brown malt which noticeably pulls the ph down. The problem with brown malt is that it can't be steeped. It has to be mashed so I can't just add it later. I'd love to know how others deal with his technique and brown malt.

 

[jbaysurfer]

RO water contains very little buffer. That means your PH meter is going to have a hard time measuring it. Doctor it with your brewing salts first, then take the PH measurement and you'll get a much better reading.

 

[frettfreak]

I have an RO setup and my water usually comes out around 5.5. It really depends on the source water as to what it will be coming out at the other end of the RO filter. 5.0 isnt really an issue as long as you know how to adjust. but jbaysurfer is correct... ro water can be tricky to get a reading from. I find it also takes a lot less of whatever you are using to adjust ph due to the lack of buffers as well.

What i did on an imperial porter i brewed the other day was use 80% tap water (filtered through a carbon filter) and use 20% tap. this worked out pretty well with the darker malts (my tap water is also hard which is supposedly ok for darker malts as well) as my mash ph stayed around 5.2.

 

[drkwoods]

ahh... the lack of buffers makes total sense. I have never had an issue with too low a pH in a mash but in that case I would probably simply add Baking Soda. Interestingly Ive had wonderful Darker beers and lackluster lighter colored beers and I think Ive dialed in the reasons since I switched to RO water from my med hard tap water. But learning how to use RO water and simply make small consistent additions is really paying off now.