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Old 02-27-2012, 01:29 PM   #1
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Default Reducing alkalinity with slaked lime

I haven't brewed in a while, and am eager to get back to brewing in late March.

In the meantime, I've been thinking about reducing alkalinity with slaked lime. Using Braukaiser.com's article, with AJ deLange as an influence, I'm reading and rereading this article: http://braukaiser.com/wiki/index.php...th_slaked_lime

I need to get the lime and the GH/KH test kit. In the meantime, I'm trying to work my head around the spreadsheets, and how much CaCl2 I have to add to have sufficient calcium to form calcium carbonate.

My understanding is that the last spreadsheet, using the GH/KH numbers, can guestimate the probable amount of calcium left. Is there anything that I'm missing?

I'm trying to think of a vessel that I can use permanently for this procedure, as once the chalk precipitates out, it doesn't matter if it stays in there, unlike my BK. I guess a large stainless pot that I no longer use would be ideal.

I see the recommendation to add chalk (to provide nucleation points), and to stir but not aerate. Any other tips?

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Old 02-27-2012, 01:45 PM   #2
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Depending on how much of your hardness is temporary and how much permanent the decarbonation process may leave you with less than the desired calcium level in which case you will want to supplement the calcium before you brew. If you plant to do that then add the extra calcium before you add the lime. This can get your alkalinity below the oft cited 50 ppm as CaO3.

It is IMO, very important to use a pH meter when decarbonating with lime and to add in enough source water to bring the pH back to 8.3. If you don't do this you may wind up with un - neutralized hydroxyl alkalinity and you are doing this in the first place to get alkalinity down. Do a web search on 'Hubert Hanghoffer lime'. Actually don't do that. If you do all you will find is references to me telling people to do that. Go here:
http://hbd.org/hbd/archive/2540.html#2540-8
and read Hubert's post. If you want to look for his website (if it's still up) it's pretty interesting too.

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Old 02-27-2012, 01:49 PM   #3
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Originally Posted by ajdelange View Post
Depending on how much of your hardness is temporary and how much permanent the decarbonation process may leave you with less than the desired calcium level in which case you will want to supplement the calcium before you brew. If you plant to do that then add the extra calcium before you add the lime. This can get your alkalinity below the oft cited 50 ppm as CaO3.

It is IMO, very important to use a pH meter when decarbonating with lime and to add in enough source water to bring the pH back to 8.3. If you don't do this you may wind up with un - neutralized hydroxyl alkalinity and you are doing this in the first place to get alkalinity down. Do a web search on 'Hubert Hanghoffer lime'. Actually don't do that. If you do all you will find is references to me telling people to do that. Go here:
http://hbd.org/hbd/archive/2540.html#2540-8
and read Hubert's post. If you want to look for his website (if it's still up) it's pretty interesting too.
Thank you! I will look at that.

You're saying to use the meter and check the pH, right after adding the lime and get it down to 8.3? Kai's instructions say that the pH should be 9-11, so I'm not questioning you- just asking for clarification!
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Old 02-27-2012, 02:11 PM   #4
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First step is to calculate the amount of lime to add. It is important in this step to include extra to neutralize any acidity in the water as well as the amount required to remove the bicarbonate. You will calculate the wrong amount. Add this to half the water. This insures a high enough pH that magnesium will precipitate. If you want to get rid of the magnesium decant. You will now have water from which you have removed calcium and magnesium but it will be very alkaline as there is approximately twice as much lime in there as you needed. This needs to be neutralized and the 'acid' in this case is bicarbonate ion from the source water. You add source water until the lime is neutralized until the pH is around 8. The acid gives up its hydrogen ion
HCO3- --> H+ + CO3-- which neutralizes an (OH-) ion forming water and the CO3-- finds a calcium with which it coalesces and precipitates out. Of course as you approach pH 8.3 a smaller and smaller fraction of bicarbonate ions give up the proton. At pH 8.3 it is only 1 % and that is why there is a limitation as to how much bicarbonate you can precipitate. Clearly you get at least half (if calcium hardness exceeds alkalinity) and the practical limit seems to be about 50 ppm as CaCO3.

DeClerck's procedure does not involve a pH meter (but probably would have if he had ones like the ones we have today available to him). He recommends calculating additions of 10% more lime and 10% less lime than what you calculate neutralizing acidity and capturing bicarbonate and then doing 3 tests on samples. Each sample is analyzed and the dose that gave the best decarbonation is scaled up to the volume of water to be treated.

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Old 02-27-2012, 02:16 PM   #5
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That makes sense! Thank you so much.

I was simply diluting my tap water 30-50% RO for most beers, but the last couple had a bit of harshness to them. I suspect that the RO "machine" at the store hasn't been maintained and I'm hesitant to try it again. We live in a small town, and that's the only one around. I can't really justify my own RO system, so I thought the slaked lime would be just the ticket- using my own good tap water (just high in alkalinity)- if it's as easy as it seems.

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Old 02-27-2012, 04:35 PM   #6
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Yes, if the water has high temporary hardness (say temp hardness > than 75% of total hardness), then a water is well suited for lime softening. As the temp hardness percentage falls in comparison to the total hardness, the suitability of lime softening diminishes. A water with high temporary hardness should not require another calcium source other than the Ca(OH)2.

Hubert's site has some basic errors regarding lime treatment, but its mostly correct. I see that he is a chemist and may not be aware of the proper calculations used in water treatment. There are additional criteria that should be considered when contemplating lime treatment. A primary issue is if magnesium removal should be performed for the water. That changes the dosing of lime, the targeted peak pH for the treatment, and if split treatment is suitable.

The next version of Bru'n Water already has lime treatment and boiling treatment calculators built in. Hopefully that version can be beta tested and issued in the next month or so.

I have started to recommend that users of vending machine RO water should have a pocket TDS meter with them so they can quickly assess if that machine is putting out 'good' water. The meters are cheap. TDS should be less than 20 ppm from a properly operating machine. Don't buy the water if its over 50 ppm.

The next version of Bru'n Water will include a TDS calculation for the user's tap water profile or treated water profile so that they can perform a quick double check of their water with a TDS meter. A typical TDS meter accuracy is better than 5%, so that tool might be worthwhile to have around. That is especially true when dealing with a water supply that might vary with time or time of year.

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Old 02-27-2012, 08:06 PM   #7
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Originally Posted by mabrungard View Post
Yes, if the water has high temporary hardness (say temp hardness > than 75% of total hardness), then a water is well suited for lime softening. As the temp hardness percentage falls in comparison to the total hardness, the suitability of lime softening diminishes. A water with high temporary hardness should not require another calcium source other than the Ca(OH)2.

A typical TDS meter accuracy is better than 5%, so that tool might be worthwhile to have around. That is especially true when dealing with a water supply that might vary with time or time of year.
My water is low in magnesium, or at least relatively low, so I don't think magnesium reduction is an issue for me. But my calcium was 57 ppm, while my CaCo3 is 228. I was thinking I'd have to add some CaS04 or CaCl2, from what I understand of Kai's article.

I think a TDS meter would be a great new toy for me! Would that "work" instead of the GH/KH tests that Kai mentions in his instructions?
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Old 02-27-2012, 08:41 PM   #8
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Sort of. They measure conductivity and convert that to weight using a calibration derived, usually, from sodium chloride. Clearly if your TDS reading goes down you have removed something but how much of what isn't so easy to say.

The alkalinity test kits are not specific for bicarbonate but as bicarbonate better be the only alkaline thing found in you municipal water an alkalinity test measures bicarbonate well. The hardness tests respond to calcium and magnesium (but also strontium and iron etc all of which should be low and thus not a significant contributor to error) and can be made to measure calcium only by dropping the magnesium first (just as you do in the softening procedure i.e. by high pH). Thus they can measure calcium and magnesium hardnesses separataely.

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Old 02-27-2012, 10:18 PM   #9
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While the TDS meter is nice to have, the hardness and alkalinity test kits are probably more valuable.

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Old 02-28-2012, 01:19 AM   #10
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This page may help: http://www.franklinbrew.org/wp/?page_id=399 (It worked for me.)

EDIT: I guess that page is a condensed version of Hubert's post(s) that AJ linked.

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