Spartan1979

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I got a pH meter for Christmas. The pH of my tap water is about 9.2. I had to add 5ml of 50% Phosphoric acid to 7 gallons sparge water to get the pH under 5.7.

Seems like a lot of acid. Does this quantity make sense?

Thanks.

day_trippr

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What kind of water system are you on?
Did you calibrate the meter before using it?

Cheers!

ajdelange

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It does if the alkalinity of the water is 81 ppm as CaCO3.

Spartan1979

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Municipal Water System. The water comes from the Missouri River.

Yes, I calibrated the meter.

Spartan1979

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Per the reports, total Alkalinity is 53 ppm

Total Hardness as CaCO3 is 99-108 mg/L

But I had to get this data from two different reports.

ajdelange

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Then, theoretically, it should only take 3 mL of 50% acid. But there are lots of reasons why the actual alkalinity you are encountering is probably not the number in the report which is most likely an average. And your measurement of pH, your measurement of the amount of acid and even the strength of the acid may not be spot on.

If you really want to know what the alkalinity of the water is you would put your pH meter into it and precisely add acid of precisely known strength to it until the pH reached 4.3. It's pretty clear that you are essentially doing just that but not being so precise. What I'm getting at is that 5 mL vs 3 mL with the latter based on a municipal water report isn't, IMO, that much of a discrepancy.

Spartan1979

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Thanks, AJ. I just wanted to be sure I wasn't way off the mark with the approximate amount of acid I was adding.

I had been using pH papers before I got my meter and only a few drops was giving me a reading in the proper range! That's why I was concerned with the amount of acid I was adding. It also helps to explain my dissatisfaction with my beers lately. My sparge water was probably well over 8.

I've thrown away the pH papers.