pH too low.

[indianajns]

I've been noticing the last 2 beers I have brewed have had a low pH for the mash, in the 4.9 range. Today I brewed a Doppelbock and I shot for a 5.3 pH in EZ water. Again, my pH was low at 4.9. I added Baking soda and this corrected me up to around 5.1-5.2. However, it was probably 20 mins into the mash before the adjustment was made and my efficiency suffered. Was wondering if anyone has any thoughts as to why my mash pH would all of a sudden drop significantly? I use RO water from an under sink unit. I change all of the filters yearly and have not had this issue previously. I have gone ahead and ordered the Ward labs testing kit to test my RO water for piece of mind but I'm not sold that it is my RO unit causing this issue.

My doppelbock recipe had 12.2 gallons of mash water and 7 gallons of sparge water.

29 lbs of munich base
8 lbs of pilsner
2 pounds of carmunich

I added 6 grams of gypsum and 8 grams of calcium chloride to the mash water and also had 3 ounces of acidulated malt. Estimated mash is 5.41. It was reading 4.9 at mash temps during the first 15 minutes of the mash before I added baking soda. I tested the pH with both the colorpHast strips AND with a pH meter I trust.
Thoughts? Thanks in Advance.

[DrDually]

What was time period between adjusting pH and retesting?
The pH may have adjusted but you checked too soon after adjusting
I have found that stabilizing may take up to 15 min

[dhempy]

How did you take your pH reading? If using a meter .. did you calibrate it before the session?

Edit: D'oh ... guess I missed your last line.

Dan

[indianajns]

Thanks for the responses guys.

What was time period between adjusting pH and retesting?

I tested multiple times. After 20-25 minutes it had adjusted up to 5.1. Doesn't most of the conversion take place in the first 15 minutes. If I am able to get it to adjust up does it make a noticeable improvement as most conversion was done before my mash pH adjusted up to 5.1?

How did you take your pH reading? If using a meter .. did you calibrate it before the session?

I used a meter and colorpHast strips. Both x-validated the other. I calibrated the meter that morning.

[brahn]

Did you cool your sample before checking pH?

Edit: nevermind, I see in your first post you said "at mash temp". When you see the recommended pH ranges that is at room temperature. As the temp rises, pH drops, so you're probably in the ballpark pH-wise.

[DrDually]

Did you cool your sample before checking pH?

Edit: nevermind, I see in your first post you said "at mash temp". When you see the recommended pH ranges that is at room temperature. As the temp rises, pH drops, so you're probably in the ballpark pH-wise.

+1

[indianajns]

How do you guys cool your mash sample used by pH meter down quickly?

[jward]

I was thinking I would make a sample tube out of copper pipe to stir in a cup of iced water but never got that far.

[SamIam]

I have some 4oz taster glasses I keep in the fridge. I swirle a couple ounces in one before I take my reading. My meter has ATC so I just try and get the temp down to around 90F. For what's it's worth, I also have used the EZ calc and have noticed that it seems to predict the pH about 0.3 higher than what I usually get.