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-   -   Alkalinity & Residual alkalinilty (http://www.homebrewtalk.com/f128/alkalinity-residual-alkalinilty-239546/)

lehr 04-13-2011 05:35 PM

Alkalinity & Residual alkalinilty
Is there a certain ppm range that these should fall in .

Thanks Pat

ajdelange 04-13-2011 07:52 PM

Generally, the lower the better. For alkalinity, the limit is 0 whereas RA can be appreciably negative (alkalinity can be negative too but if it is the water is probably not fit for brewing though exceptions to that too are possible). Alkalinity is a measure of buffering capacity of the water i.e. it's ability to resist pH reductions by added acid as from malt. Residual alkalinity is the amount of alkalinity which has not been offset by hardness (which reacts with malt phosphate to produce acid and thus reduce mash pH). In brews except ones laden with dark malts it is necessary to add acid in some form to effect a desirably low mash pH. The more alkalinity the more acid will be required. Hence the general rule "alkalinity = bad". Since hardness offsets alkalinity (RA = alkalinity - hardness/3.5) I used to have the companion rule "hardness = good" but people got a little carried away with this thinking that 200 units of alkalinity was no problem if they simply dosed in 700 units of hardness (e.g. 1.2 grams of gypsum per liter of water) which led to some pretty crunchy beers. As evidence that the best beers are made with the softest water has mounted I have dropped that rule.

Now it is well known that many, if not all, beer styles evolved based on the available water it stands to reason that various styles were brewed with water with particular alkalinity/RA. The chart at
illustrates this. Here various brewing cities names are plotted against the reported local water's alkalinity and hardness. As RA = alkalinity - hardness/3.5 it is possible to show lines of constant RA on this chart as having slope 1/3.5. If a brewer is a real stickler for authenticity he can, guided by this chart, prepare, say, Vienna water for the purpose of brewing a VMO. However there is the question of how one gets to a particular alkalinity and hardness and thus RA. This is somewhat difficult involving dissolving chalk in base water using CO2 gas. Unfortunately many undertake this process ignoring the CO2 (how many spreadsheets have you seen that calculate the CO2 requirement) with results that are far from the targets (and the target data are frequently in error). Given that it is not necessary to do all this it is often simpler to just say that alkalinity should be 0 and RA around -30 (representing about 50 mg/L Ca++).

mabrungard 04-13-2011 08:09 PM

I agree with AJ, brewing water should have only the alkalinity needed to produce a decent mash pH and resulting beer pH.

I have to comment on the chart AJ has assembled. It includes several water profile results that are not feasible and there is considerable scatter in the results do to that. At AJ's suggestion, I included a version of that same RA chart on the Adjustment Summary sheet of Bru'n Water. With the cleaned up information on water profiles that I've compiled, I was also able to plot the water RA results for those various Cities. AJ's chart above does show some of the same results, you just can't see it.

The point I'm trying to make is that there are distinctive trends in the results that relate to those profiles with high temporary hardness and those with high permanent hardness. You'll need to download the current version of Bru'n Water to see what I'm talking about. High temporary hardness waters tend to plot on a relatively steep line within the chart, while the high permanent hardness waters tend to plot along the 1/3.5 lines that AJ mentions. All this doesn't really amount to a hill of beans, but I figured it was an interesting thing that brewers might not be aware of.


lehr 04-14-2011 10:22 AM

Thank you both it nice to get answers from the" Rocket scientists" of water science. Btw Aj I'm sending in another sample to be tested I've had my softner off line for a couple weeks I will report the finding when I receive them.

Thanks again

lehr 04-15-2011 12:03 PM

Aj and Martin, I was talking to a friend about this post who works for a local water treatment plant and now has me a bit confused. Referring to the last line in Aj's reply (simpler to just say alklinity should be 0 and ra -30 ) so if I build my water on ez water and my numbers come out 0 alklinity and -30 ra
my water should be good correct.

Thank again

mabrungard 04-15-2011 01:02 PM

0 and -30 are desirable for a pale colored beer with little crystal malt, but may produce a sharper and tarter beer than desired if dark malts or crystal malts are in the grist. Just using those values will not suit all beer styles. That is why a tool like Bru'n Water is useful. It allows you to see the effect of the grist and helps you estimate what your water adjustments may be. The best tool will still be a pH meter, but Bru'n Water will consistently get you in the ball park.

ajdelange 04-16-2011 02:32 AM


Originally Posted by lehr (Post 2839801)
.. so if I build my water on ez water and my numbers come out 0 alklinity and -30 ra
my water should be good correct.

There's a bit more to it than that. Zero and -30 just happen to be the alkalinity and RA numbers for DI/RO water to which about 3 grams of calcium chloride have been added per 5 gallons treated. Such a water will, in most cases, make a good beer if the proper amount of acid (as sauermalz: 2-3% for light lagers; 1-2% for ales; none for stouts) is added. This is important as the most significant thing you can do to improve your beer is to get mash pH into the correct range. The details are in the Primer.

kladue 04-16-2011 04:32 PM

Has anyone explored the blending of calcium citrate with the traditional calcium carbonate to increase calcium solubility and dispersion in the mash. I am looking for a way to formulate and use a pill press to compact the mixtures so they can be automatically added to the malt before milling and addition to mash tun.

ajdelange 04-16-2011 05:01 PM

I'm not quite sure what you are thinking of here. If the goal is to get more calcium to dissolved you would use a soluble calcium salt such as the chloride or citrate (moderately soluble) but not in the presence of ions with which it forms insoluble precipitates such as carbonate and phosphate.

kladue 04-16-2011 05:17 PM

I am looking for an alternative to trying to carbonate calcium carbonate to increase the solubility. Calcium chloride is soluble but by the time the calcium target is hit the chlorides would be high. I would expect that the citrate component of the calcium citrate would drop Ph a bit and may be counter productive if a carbonate is not added to counter balance citrate acidity.
The initial goal is come up with a way to integrate water chemistry control into the brewing system formulation and process control application that I am working on for my system. The methods and formulas are not difficult, and implementing them was a matter of creating a couple tables and some calculations, just curious if there were any others that have explored this avenue of calcium addition without resorting to brew time chemistry experiments with CO2.

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