RO water additions and pH results

[user 157712]

Hello all...
Since switching to AG about a year back, I've been using 5.2 stabilizer and tap water with decent results, but still find I'm just really not ok with not knowing what's going into my brew. So for my latest beer I decided to try AJ Delange's suggestions in the water chemistry primer. I brewed a blonde ale using (store bought) RO water and the recommended additions for a pils style beer...calcium chloride & acidulated malt. Out of curiosity I checked the mash pH with a test strip and found it to be around 4.6 (the lowest on the color key). So, my question...Does RO water pick up ions from the air that cause a drop in pH due to lack of buffering power from the water? Are the test strips really just that crappy? Am I nuts? I guess I was not expecting a pH that low...

I hit all my usual numbers just fine with that beer and its fermenting just fine but is it going to be ok? Will it be drinkable?

Thanks all for the help!

 

[grathan]

I used RO water last week for the first time and thought the PH was low.
mabrungard explained something about it having more acid levels.

https://www.homebrewtalk.com/f36/ph-woes-406584/#post5131583

 

[Yooper]

Are the test strips really just that crappy? Am I nuts? I guess I was not expecting a pH that low...

Yes, if your pH read 4.6 on the strips then they are just that crappy.

 

[BrewKnurd]

I used RO water last week for the first time and thought the PH was low.
mabrungard explained something about it having more acid levels.

https://www.homebrewtalk.com/f36/ph-woes-406584/#post5131583

But he was taking about the pH of the water. Since ro is so low in minerals, it's easy for it's ph to swing, but that doesn't mean the mash ph changes accordingly.

 

[user 157712]

Thanks for the replies.

The brewing process up to this point has come pretty easy, but this is the last chapter in Palmer's book that just has me feeling like a dummy. Having a technical background makes this extra maddening for me Makes me wish I would have had more of an interest in high school chemistry.

I kinda figured having basically no minerals in the water made RO more sensitive to changes the closer you got to 7. I guess if I really want to be sure of my pH levels I need to get some decent test equipment. What do you guys use/recommend? Also...any good books relating chemistry to brewing?

 

[Yooper]

These aren't books, but are very helpful: https://sites.google.com/site/brunwater/

http://braukaiser.com/wiki/index.php?title=How_to_read_a_water_report

 

[ajdelange]

Hydrogen ions are small and so pass through RO membranes more easily that OH ions so there is a small shift in pH from the RO process itself but the main effect is that the buffering capacity (alkalinity) of RO water is small so that the small amount of CO2 which dissolves in it can shift its pH noticeably. But the buffering capacity is still very small and you do not need to worry about this shift. This 'acid' will be overwhelmed by the buffers in the malts.

pH strips are notorious for reading low though some are better than others. A brewer needs a thermometer, a hydrometer and a pH meter.

As for info for the technically inclined try www.wetnewf.org. The 'Articles' tab has a few pages on some of the basics plus some of the newer things I've found out in researching some stuff for Palmer's upcoming water book. For more in depth treatment go to the 'PDFs' tab and check the two part article on Alkalinity. The Cerevesia article is a more formal, in depth, review of mash tun/water chemistry.

 

[user 157712]

Thanks a lot! I will give those links a look.