[KilroyWasHere]

Hi all,
I have been using Bru'n water for my BIAB brews and have run into an issue that I cannot make sense of. I use a 3/4 dilution of distilled and tap water for all of my recipes. My tap water is filtered and softened, resulting almost no mineral content except for the sodium and chloride from the softener. Na/Cl is 184/170, then of course those are reduced to 1/4 of through the dilution. Tap ph is 7.2.

I have found for dark beers Bru'n water is pretty much right on for mineral additions, hardly ever requiring any acid addition. For light colored beers, and only recently, I am finding that I am needing to at least double the amount of acid that Bru'n water predicts to hit mash ph. Not from 2 to 4 ml, but form 20 to 50 ml!

I use 10% phosphoric, diluted down at home from 85% phosphoric that I obtained. I calculate the dilutions simply by equating the products of the volume and percent acid and solving. So the ratio of the volume of 10% to 85% is 8.5. I have a 1/2 liter bottle I use for dilutions so I measure out 50 ml of 85% acid, then fill to 425 ml. Should be right.

I trust the accuracy of Bru'n water, and I also immediately assume I must have done something wrong .
The only thing that makes sense to me is that I recently realized I was diluting my acid using tap water and I should have been using distilled (?). So I think since doing my last dilution of acid with distilled water my acid is much weaker than when I diluted with tap water? The obvious thing is toss it and make up a new dilution but I thought I would check with the experts first to see if I can learn something.

Can anyone offer any insight or does this make any sense to anyone?
Thanks in advance   

[denny]

You should contact Martin for his thoughts

[mabrungard]

Assuming that the acid's concentration is indeed 85% as reported, the other variable is the alkalinity of the tap water.  I agree that you're doing the dilution correctly using the formula C1 x V1 = C2 x V2 and that does show that adding a 50ml dose of 85% acid and then filling the container with distilled water until its volume is 425ml, is correct. 

I recommend that you obtain an Alkalinity testing kit used for aquarium use and test your tap water.  It may have varied from what the original lab testing may have reported.

[KilroyWasHere]

Assuming that the acid's concentration is indeed 85% as reported, the other variable is the alkalinity of the tap water.  I agree that you're doing the dilution correctly using the formula C1 x V1 = C2 x V2 and that does show that adding a 50ml dose of 85% acid and then filling the container with distilled water until its volume is 425ml, is correct. 

I recommend that you obtain an Alkalinity testing kit used for aquarium use and test your tap water.  It may have varied from what the original lab testing may have reported.

Thank you Martin, I will  check that. I am not connecting the dots on the alkalinity though. If I switched from diluting the acid with tap to distilled, and the rest of the process is the same, why the change in acid additions? Or are you implying that the change in my acid dilution coincided with a change in my tap alkalinity?

Either way I will check the alkalinity per your recommendation. Thanks again.

[KilroyWasHere]

I followed Martin's recommendations regarding an alkalinity test kit. I tested my tap alkalinity, which resulted in 5 dKH. That apparently is equal to 89 ppm, although the online calculator does not tell me if it is CaCO3. Assuming it is, this is a change from 127 per my original water report.

I then went into the spreadsheet and reduced the bicarbonate until the total alkalinity was 89. That resulted in a ph drop from 5.49 to 5.44 on a grain bill for a Dubbel I am brewing. Does that make sense?



 

[mabrungard]

I’m hoping that you diluted the acid with distilled water. If not, the diluted acid concentration could be anything.

[KilroyWasHere]

I’m hoping that you diluted the acid with distilled water. If not, the diluted acid concentration could be anything.

Thanks Martin, yes I am now using distilled. Previously I had been using tap. Since switching to distilled for acid dilution I have found I need much more acid for the light color beers.