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-   -   Water. DH 6/KH 2 NE Ohio. That sound reasonable? (http://www.homebrewtalk.com/f128/water-dh-6-kh-2-ne-ohio-sound-reasonable-379827/)

Hermit 01-09-2013 01:42 AM

Water. DH 6/KH 2 NE Ohio. That sound reasonable? UPDATED with more testing
 
Reservoir water so it will vary. I always thought the white build up in things like my toilet tank were calcium deposits yet this seems to indicate low calcium? I live in an area where my Starsan turns while from the water hardness. I have a PH meter on the way later this week but I guess I'm into the area of worrying about yeast health? According to Kai's worksheet I need to up my calcium some if I understand it correctly.

Hermit 01-20-2013 08:11 PM

Did some testing today and things get a little stranger for someone that doesn't understand water treatment I guess.

Tap water.
GH 6
KH 2
pH 10.61

RO water
GH 1 (Turned color on the first drop added)
KH 2
pH 10.88

RO Waste Water (I run it into a barrel)
GH 7
KH 2
pH 10.38

I first noticed the high pH level when I got my meter and was using the RO to rinse the probe. This is what prompted me to run the tests. The KH is a little baffling but it might be the test is just not the sensitive.

ajdelange 01-21-2013 12:38 PM

Total hardness of 107 and alkalinity of 35 imply the presence of sulfate and/or chloride. I'm sure the post RO hardness is less than 18 but that is consistent with it turning color on the first drop in a drop count kit. OTOH I am sure that the alkalinity is not still 35. Drop count kits are not that accurate. Equipped with a pH meter you should be able to measure alkalinity yourself quite easily and more accurately.

Kaiser 01-21-2013 02:16 PM

the pH of tap water should not be that high. I think 9.5 is the highest that the EPA allows.

And yes, the drop kits have an inherent error which is particularly noticeable when you need only a few drops. You could increase the precision by taking twice the sample volume and dividing the drop count by two. But that doesn't get rid of the systematic error caused by drop sizes that are not the same size as intended by the manufacturer.


Kai

Hermit 01-21-2013 02:19 PM

Quote:

Originally Posted by Kaiser (Post 4808943)
the pH of tap water should not be that high. I think 9.5 is the highest that the EPA allows.

Kai

I was more than a little surprised by that to be honest. So far my request from the water department for water analysis has met with total silence.

Kaiser 01-21-2013 03:29 PM

Quote:

Originally Posted by Hermit (Post 4808950)
I was more than a little surprised by that to be honest. So far my request from the water department for water analysis has met with total silence.

With a pH that high you are getting ~22 ppm as CaCO3 alkalinity just from the pH alone. I.e. it takes 22 ppm as CaCO3 worth of a strong acid to lower the pH to 4.3. With a pH of 9 it would only be 3 ppm as CaCO3.

Kai

ajdelange 01-21-2013 06:47 PM

Actually it's 8.5 but it is a secondary MCL and it is not that uncommon to see it busted.
I get a different number for the alkalinity. At 20 C pOH = 14.165 - 10.61 = 3.555 so OH- concentration is about 10^-3.355=.2786 and it would take that much acid to neutralize it. In ppm as CaCO3 .2786*50 = 13.9. Another 2.5 ppm of acid would be required to establish the H+ concentration at pH 4.3 giving a total of 16.4 for the 4.3 alkalinity of a solution which contains only strong base. Since my number was different I started pouring over my spreadsheet looking for inconsistencies and didn't find any but I did find another mistake so I'm happy this came up.

I said in #3 that one ought to be able to measure alkalinity at home more accurately that with a drop count kit and that got me wondering what it might take starting from scratch or starting from scratch except that one owns a pH meter. Doesn't look too bad ($50 - $102). I put some comments and links to the necessary equipment/materials at http://www.wetnewf.org/pdfs/measuring-alkalinity.html.

Kaiser 01-21-2013 08:35 PM

Quote:

Originally Posted by ajdelange (Post 4809872)
Another 2.5 ppm of acid would be required to establish the H+ concentration at pH 4.3 giving a total of 16.4 for the 4.3 alkalinity of a solution which contains only strong base.

I was working with pOH = 14.0 - pH. Using 14.165 gives me the same result.

Thanks for pointing that out.

Kai

ajdelange 01-21-2013 08:38 PM

I'm surprised it makes that much difference but I guess I shouldn't be. That's the effect of a 5 C change in temperature.

Kaiser 01-22-2013 02:20 PM

Quote:

Originally Posted by ajdelange (Post 4810242)
I'm surprised it makes that much difference but I guess I shouldn't be. That's the effect of a 5 C change in temperature.

This is all b/c of the logarithmic relation between pH and actual H+ and OH- concentration. A small shift in pH or Kw can make a big difference in the result. But 16 ppm as CaCO3 doesn't cause much of a pH shift in the mash.

Kai


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