Author Topic: Salt calculation  (Read 2475 times)

Online hopfenundmalz

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Re: Salt calculation
« Reply #15 on: February 25, 2013, 04:30:35 PM »

Can you explain your error analysis in more detail?
I use 1 and 5 gallon jugs, and know the levels in my kettles. I have a 100 gram capacity scale with a 0.01 gram resolution. My water volume and salt mass additions should be pretty close.

expensive laboratory graduated cylinders are +/- 5% accuracy.  I'd expect your 1 or 5 gallon jug to be much worse.  using a small vessel to measure volume multiple times increases your error even more.

have you ever calibrated your scale?

I have a 100 gram mass that goes on each time. Usually get one part in 10,000 error. Good enough for homebrew?
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Offline tschmidlin

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Re: Salt calculation
« Reply #16 on: February 25, 2013, 04:46:00 PM »
Can you explain your error analysis in more detail?
I use 1 and 5 gallon jugs, and know the levels in my kettles. I have a 100 gram capacity scale with a 0.01 gram resolution. My water volume and salt mass additions should be pretty close.
I'm not sure what was specifically meant, but CaCl at least has a tendency to suck moisture from the atmosphere and weigh more than it should on a ppm basis.  If you leave it open and live somewhere humid . . . well, there's a reason it is used as a dehumidifier. :)
And Epsom salt is MgSO4,  is it MgSO4·7H2O?
I hope Martin can lend some knowledge here.
Typically I think it is 7H2O, but whatever form it is, it is not hygroscopic like the CaCl is.  Most salts are fine I think, unless maybe you live somewhere ridiculously humid.  Even table salt will pick up moisture in a really humid area, or at least that is the explanation given for the grains of rice in the salt shakers at the beach.
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Re: Salt calculation
« Reply #17 on: February 25, 2013, 04:55:20 PM »
Can you explain your error analysis in more detail?
I use 1 and 5 gallon jugs, and know the levels in my kettles. I have a 100 gram capacity scale with a 0.01 gram resolution. My water volume and salt mass additions should be pretty close.
I'm not sure what was specifically meant, but CaCl at least has a tendency to suck moisture from the atmosphere and weigh more than it should on a ppm basis.  If you leave it open and live somewhere humid . . . well, there's a reason it is used as a dehumidifier. :)
And Epsom salt is MgSO4,  is it MgSO4·7H2O?
I hope Martin can lend some knowledge here.
Typically I think it is 7H2O, but whatever form it is, it is not hygroscopic like the CaCl is.  Most salts are fine I think, unless maybe you live somewhere ridiculously humid.  Even table salt will pick up moisture in a really humid area, or at least that is the explanation given for the grains of rice in the salt shakers at the beach.
So I am doing the right thing with the airtight jars for the salts? The wife has a hard time getting the lids off of those.
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Offline tschmidlin

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Re: Salt calculation
« Reply #18 on: February 25, 2013, 04:57:58 PM »
So I am doing the right thing with the airtight jars for the salts? The wife has a hard time getting the lids off of those.
I think so.  I keep my CaCl in an old mayo jar, the CaSO4 just sits in the bag.  I don't even use the CaCO3 or MgSO4 anymore.
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Re: Salt calculation
« Reply #19 on: February 25, 2013, 05:12:31 PM »
So I am doing the right thing with the airtight jars for the salts? The wife has a hard time getting the lids off of those.
I think so.  I keep my CaCl in an old mayo jar, the CaSO4 just sits in the bag.  I don't even use the CaCO3 or MgSO4 anymore.

The chalk I have, is on the shelf. No longer used by me. Maybe a friend that still does some rock climbing will like that. For brewing pickling lime is where it is at if you want to raise the pH. But you know that.

I only use Epsom salts on rare occasions. I know you get the Mg the yeast need from the mash.
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Offline tschmidlin

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Re: Salt calculation
« Reply #20 on: February 25, 2013, 05:35:28 PM »
If not the mash then there should be enough Mg in the nutrient I always use. :)

I still haven't used pickling lime, we have great water and according to Bru'n Water I don't need it.  So I've got that going for me, which is nice. ;)
Tom Schmidlin

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Re: Salt calculation
« Reply #21 on: February 25, 2013, 05:51:15 PM »
expensive laboratory graduated cylinders are +/- 5% accuracy.

Huh? I have student-grade cylinders and while the specs vary, none of them is close to ±5% for any reasonable volume. They're all ±0.1-0.5%, give or take, in the middle of their ranges.
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Offline tschmidlin

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Re: Salt calculation
« Reply #22 on: February 25, 2013, 06:03:40 PM »
expensive laboratory graduated cylinders are +/- 5% accuracy.

Huh? I have student-grade cylinders and while the specs vary, none of them is close to ±5% for any reasonable volume. They're all ±0.1-0.5%, give or take, in the middle of their ranges.
Thanks for checking.  5% seemed high, but I'm not at the lab so I couldn't check any we have on hand.  I should have just checked fisher, the two I looked at were 0.5% and 0.3% (0.5 ml for 100 ml cylinder and 3 ml for a 1000 ml cylinder).  Of course if you try to measure 10 ml in that 100 ml cylinder, that's 5%.
Tom Schmidlin

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Re: Salt calculation
« Reply #23 on: February 25, 2013, 07:05:43 PM »
So having said that, I have a copy of Bru'n Water on my computer which I open periodically.  It is just too complex and intimidating for me at this stage of my understanding.  The reason I use EZ Water is because it is easy.

Steve,

You may want to look at this: http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/

It is designed for easy entry but can do as little or as much as you expect from a water calculator.

as for getting 100 ppm, it depends on what you want to be at 100 ppm.

Kai

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Re: Salt calculation
« Reply #24 on: February 25, 2013, 09:29:13 PM »
So having said that, I have a copy of Bru'n Water on my computer which I open periodically.  It is just too complex and intimidating for me at this stage of my understanding.  The reason I use EZ Water is because it is easy.

Steve,

You may want to look at this: http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/

It is designed for easy entry but can do as little or as much as you expect from a water calculator.

as for getting 100 ppm, it depends on what you want to be at 100 ppm.

Kai

Yes, I've been looking at that.  It looks very intuitive.  I also enjoyed your podcast on the new water calculator on Basic Brewing Radio.  You have been very informative there.  I have listened to your two podcasts from 2011 with him on mash pH at least twice.  Thank you!
Steve

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Re: Salt calculation
« Reply #25 on: March 01, 2013, 09:39:05 AM »
expensive laboratory graduated cylinders are +/- 5% accuracy.  I'd expect your 1 or 5 gallon jug to be much worse.  using a small vessel to measure volume multiple times increases your error even more.
You're thinking of the error on flasks and beakers, which is due to mass production and not being designed for measuring.  It is easy to get better accuracy in large vessels if you calibrate each one yourself. 5% of 5 gallons is 1 quart - that's 1/2 inch of water in my brewpot.
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