alkalinity as CaCO3

[pjj2ba]

Carbonate/Bicarbonate buffers are typically used in the range of pH 8-11, so yeah one would expect a much higher pH. I agree that you may need more CaC03 to see the difference. How fizzy was the water after adding the CO2? Maybe there is extra carbonic acid as a result of the CO2 addition and this is keeping the pH lower than would be expected. If you left sample C out to allow for the extra CO2 to leave, then the pH should go up I would think. Maybe that is what you saw with sample B. As the low level of natural dissolved CO2 was consumed, then the pH went up.

 

[Kaiser]

How fizzy was the water after adding the CO2?

Fairly fizzy. I assume it was saturated with CO2 at 1 bar pressure. There was also a sudden release of CO2 when I added the malt. The pH of water C was ~5.0 but it seems that it causes a higher mash pH than water B.

Maybe there is extra carbonic acid as a result of the CO2 addition and this is keeping the pH lower than would be expected. If you left sample C out to allow for the extra CO2 to leave, then the pH should go up I would think

Next time I’ll prepare the waters in advance and let the extra CO2 in water 3 escape. Just to make sure it is not messing with the mash pH and to create a more “natural” high alkalinity water.

But I still have to explain this to myself? Why is the chalk added to the mash less potent than the chalk dissolved in the water? Both can neutralize the same amount of acid. And at mash pH conditions chalk is pretty soluble (http://en.wikipedia.org/wiki/Calcium_carbonate).

Kai

 

[conpewter]

Thanks for this thread guys, I've really been trying to understand CaCo3 and alkalinity since I have very high bicarbonates in my water and I'm trying to use as little distilled as I can, which means I'd like to add Acid but of course I need to know how much acid to use, so I'm trying to learn as much as possible.

But I still have to explain this to myself? Why is the chalk added to the mash less potent than the chalk dissolved in the water? Both can neutralize the same amount of acid. And at mash pH conditions chalk is pretty soluble (Calcium carbonate - Wikipedia, the free encyclopedia).

Could this be because there are other buffers in there (phosphates) that the mash needs to overcome before they can work on the chalk?

 

[Scotty_g]

If you want to lower the alkalinity of your water that has high bicarbonates, you can dilute (which you're doing), add slaked lime, or boil it. If you add acid (lactic or HCl) you'll consume some of that alkalinity and generate CO2, which will largely evaporate from your mash.

 

[Kaiser]

Could this be because there are other buffers in there (phosphates) that the mash needs to overcome before they can work on the chalk?

Those phosphate buffers reach acidic. This means that they actually help in consuming the alkalinity that has been added by the chalk.

Kai

 

[conpewter]

If you want to lower the alkalinity of your water that has high bicarbonates, you can dilute (which you're doing), add slaked lime, or boil it. If you add acid (lactic or HCl) you'll consume some of that alkalinity and generate CO2, which will largely evaporate from your mash.

If I consume some of that alkalinity then won't it be easier for the mash to drop the PH? I do use FiveStar 5.2 but I have 300 ppm bicarbonates, so I can't do lighter beers without dilution (Well.. good lighter brews)

Also pertaining to the original discussion I think that CaCo3 is going to add 1000ppm of acid reducing power (if that makes sense) since even if you don't have enough Co2 in solution to make two HCo3 then when you add the grains they will have enough free H+ to use up the rest of the alkalinity provided by the chalk. Of course this is only if you don't have a huge amount of chalk for the mash neutralize.

 

[Scotty_g]

If I consume some of that alkalinity then won't it be easier for the mash to drop the PH? I do use FiveStar 5.2 but I have 300 ppm bicarbonates, so I can't do lighter beers without dilution (Well.. good lighter brews)

Also pertaining to the original discussion I think that CaCo3 is going to add 1000ppm of acid reducing power (if that makes sense) since even if you don't have enough Co2 in solution to make two HCo3 then when you add the grains they will have enough free H+ to use up the rest of the alkalinity provided by the chalk. Of course this is only if you don't have a huge amount of chalk for the mash neutralize.

You are exactly right--if you add acid, it *will* make it easier for the malt to drop the mash pH. This allows you to use light-colored (low-acid) malts and still hit 5.2. In the days before water science, beer color evolved to match the water. It's not just that the folks in Dublin liked black beer that Guinness ended up that way; they needed the acid from the roast barley to neutralize their alkaline water. In Plsen (sp?) they could get a good pH with only pale or base malt--hence the pilsner.

So, given your water (whatever it is) you either modify it (add salts or acid, dilute, boil, soften) or make whatever beer is appropriate.

As far as malt gobbling up and dissolving all the chalk you throw in (or vice versa), that's not a given. Malt acids and most brewing salts are not strong acids/bases, which means they will not tend to react fully. When you dissolve HCl (hydrochloric acid, a strong acid) in water it gets rid of H+ like a bad habit--it dissociates almost completely, almost immediately. Dissolved CO2 (H2CO3, to make it easy) is not as strong of an acid...it will get rid of one H+, maybe. But a lot of it will hang around. If there's something convenient there to take up the H+ (like OH- from NaOH), then it will react quickly. The same thing goes for bases. CO3-- is a fairly strong base.

HCO3- is in between a kind of strong acid and kind of strong base. If there's a stronger acid present (vinegar, or acetic acid) it will add the H+ back in (and neutralize acid). If there's a shortage of acid (free strong bases), it will give up the other H+. Because this intermediate ion can act as an acid or a base, it helps stabilize the pH and acts as a buffering agent.

Phosphate buffer (the 5.2) contains HPO4-- and either PO4--- or H2PO4-. This means it can unload its last H+ if needed to neutralize alkalinity, or soak up H+ coming off your malt.

 

[conpewter]

Wow thank you for that explanation (Also sorry Kai for jacking your thread some) I just realized the bicarbonates are buffers just like phosphates are, not inherently a base or an acid themselves (though as you mentioned they work as one depending on the other things present).

 

[Kaiser]

I reran the experiment, just to confirm my previous findings:

• water A: reverse osmosis
• water B: RO + 160 ppm CaCO3 + 580 ppm CaCl2*2H2O
  • RA = -4.4 dH or 80 ppm alkalinity as CaCO3 if chalk adds 1 alkalinity equivalent
  • RA = 0 dH or 0 ppm alkalinity as CaCO3 if chalk adds 2 alkalinity equivalents
• water C: water B + CO2
  • RA = -4.4 dH or 80 ppm alkalinity as CaCO3 if chalk adds 1 alkalinity equivalent
  • RA = 0 dH or 0 ppm alkalinity as CaCO3 if chalk adds 2 alkalinity equivalents

I then heated both samples to 68C, added 50g crushed pilsner malt to each and rested (with occasional stirring) them for 10 min. After that I took 15 ml samples and cooled them to 20-21C:

* mash A : pH = 5.67
* mash B : pH = 5.47
* mash C : pH = 5.66

So it appears that dissolving the chalk in the mash water changes its alkalinity potential. undissolved chalk has less alkalinity potential than dissolved chalk since mash B showed a much lower mash pH which could only have been the result of a lower RA than the 2 other mashes.

But why is this? Does not all the chalk dissolve in the mash as commonly assumed? And if yes why is that? And would it always be 50%?

Kai

 

[jbford]

High alkalinity water can be used for light beers as long as it does not taste too "salty". Just add 2 tsp lactic acid per 5 gal water. This adds no extra "salt" to the water and gets the pH down.

Phosphate buffers may be adding Na or K to the water which may not be desirable. They will precipitate the Ca from the water.

One tsp of CaSO4 can be used instead for darker beers.