Reverse osmosis low mash ph

[Virtus]

I dont understand something with reverse osmosis and bruns water calc. TDS meter give me reading of 6 ppm which is ok so reverse osmosis is ok. I have also calibrated ph meter with ph solution 7 and 4. I assume that reverse osmosis have low buffer capacity, so how its possible that bruns water give me mash ph 5.65 just with reverse osmosis water?

MASH WATER 175 L

Calculated in bruns water for reverse osmosis:

CaSo4 35g
CaCl 20g
Baking soda 4g

Water output: Ca 80; Mg 0; So4 115; Na 5; Cl 57; HCO3 15

Estimated mash Ph= 5,5

Problem is that I get real mash Ph 5.1 and i dont understand why. Maybe because RO water sits outside in a barrel for approx four days before brewing? Is something wrong with my gypsum and i add it too much? But my scale libra is also calibrated...

Thanks

 

[Yooper]

What's the grain bill and that batch size? That's a lot of CaS04 and CaCl, so you're making 15 gallon batches?

And at what temperature are you taking your pH readings? Are you sure your meter is accurate?

 

[Virtus]

What's the grain bill and that batch size? That's a lot of CaS04 and CaCl, so you're making 15 gallon batches?

And at what temperature are you taking your pH readings? Are you sure your meter is accurate?

I am running small brewery 60 gallon per batch.

Grain bill is:
86 lbs pale ale malt
6 lbs aromatic malt

46 gallon mash and 27 gallon sparge. sparge is ro water. I add rest of salts in preboil because of sparge dilution.

I was taking reading at 77 fahrenheit with ATC ph meter.

 

[Yooper]

Ok, with pale malt and aromatic malt, in RO water you definitely wouldn't need baking soda- I suspect your pH meter is somehow drifting or not reading right. Did you check the meter in the buffer after taking that reading? When in the mash did you take the reading?

 

[day_trippr]

Plugging all those numbers into BW I'm getting 5.46 predicted mash pH using my own RO water settings, so pretty close.
Playing around with the color ratings really doesn't move the needle much.
Not sure what's going on in this case...

Cheers!

 

[Virtus]

I didnt check the reading in buffer, but i calibrated it before measuring. I take the reading after 25 min in mash. Really dont know what happening here. I will buy new ph meter...

I was advised to add some buffering in mash for bonding tannins from new variery hops, but these can be done also later.

 

[DownHillonWater]

@Virtus: You are correct that RO water has no buffering capacity but the extracted malt has lots.

I think your pH meter is fine. If you are storing it properly in solution, calibrate it with the standards and measure them reproducibly, this is very unlikely an issue.

I build up from RO water just as you do with very similar proportions. I typically wouldn't add any bicarb for such a light beer, but you are adding very little. My pH readings are often more acidic than predicted, but not to the same degree that you see. And 5.1 is pretty low pH. Are you measuring the wort after collection? I usually measure the mash about 15 min in. The first runnings, the last runnings and the total wort. Also best to be close to room temperature when measuring...

 

[Virtus]

I measuring mash ph 20 minutes in mash at 77 fahrenheit last time. Really dont know what is going on with my ph. I red that people adding acid in RO, these is something what i dont understand, because RO have zero Alkalinity and zero HCO3...

 

[DownHillonWater]

I think you should measure your pH of the collected wort before doing anything radical. I typically measure after a couple gallons collected w/ batch size of 5 gallons. Then I measure during sparge and total collected wort. I wonder if there is a gradient of pH across your grain bed?

 

[Virtus]

I think that is ok if i measure 20 minutes after mash when conversion is almost done and at the end of the mash. Last time ph was the same at 20 min and at the end. Just ordered new ph... Can somene explain me why some people add acid or acidulated malt in mash when brewing with reverse osmosis with HCO3 near zero? End if you add salts in RO, specially CaSo4 these brings buffer capacity down and mash ph is then lower.

 

[joe_sallo]

I am running small brewery 60 gallon per batch.

Grain bill is:
86 lbs pale ale malt
6 lbs aromatic malt

46 gallon mash and 27 gallon sparge. sparge is ro water. I add rest of salts in preboil because of sparge dilution.

I was taking reading at 77 fahrenheit with ATC ph meter.

 

[Virtus]

I dont see your quote