Bicarbonate calculations off in water calc

Discussion in 'Recipe Editor' started by Nosybear, Aug 2, 2020.

1. Nosybear Well-Known Member

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#1
I switched over to RO water and so began to add bicarbonate to bring the water up to the balanced profile. Adding 4g to my 5 gal batch resulted in a change of less than 1 ppm. I did the calculations by hand and, in my 8.75 gallons of water (33l), it should have added 87 ppm of bicarbonate. (adding 4g of baking soda, molar weight 84, 61 of which are bicarbonate equaling 2.9 g bicarbonate, divided by 33 liters = 0.088g/l = 88 mg/l, or ppm).

2. Pricelessbrewing QA Software Tester Staff Member

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#2
@Yooper Can you take a look, and open a ticket if we're able to replicate. Sounds like something that we should hotfix asap.

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#3
Can you give me a link to that recipe so I can dig into it right away?

4. Nosybear Well-Known Member

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#4
Here you go....
https://www.brewersfriend.com/homebrew/recipe/view/543869/petit-session-saison
Another issue I noticed while using tap water is that the bicarbonate in the tap water is not reflected as bicarbonate in the recipe. Bicarbonate serves two purposes: It adjusts pH but it adjusts flavor as well. So the hardness as CaCO3 should reflect as bicarbonate in the water calculator as well as adjusting pH.

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#5
Thanks for letting me dig into this.
The water calculator is working perfectly.
It definitely adds 85 ppm bicarbonate to your water when you add 4 grams of baking soda.

Without baking soda:

It's all set.
But then you added 5.56 ml of lactic acid to counteract the added bicarbonate:

Remember that the point of adding acid is to neutralize the bicarbonate (alkali) so that your mash pH is acceptable. There is NEVER a target for bicarbonate, except that which is needed to get the pH in the proper range.

The lactic acid is doing exactly what it is added to the water to do- neutralizing the alkalinity.

@Pricelessbrewing This is the reason I've been so against having auto-calcs done. To hit a "profile" means adding bicarbonate, and then adding acid to eliminate the bicarbonate.

Adding alkali and acid both to the recipe counteract each other. However, when you add baking soda, you also do gain some sodium and some people feel it can be desirable in certain recipes, so that can be done to add sodium (most people would use sodium chloride to add sodium without bicarbonate, though).

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6. Nosybear Well-Known Member

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#6
Adding acid does not eliminate the bicarbonate. it lowers the pH, favoring bicarbonate over carbonate in the solution. I don't know why but when I entered the 4g of baking soda I got 0.74 ppm bicarbonate. It also threw off the acid calculations, leaving my pH about 0.2 points high. Had I got the 84 ppm, I wouldn't have done the manual calculations! I understand pH adjustment and offsetting alkalinity with acid. But be gentle with me - it's my first RO batch!

7. Nosybear Well-Known Member

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#7
Here's what I got:

You see I have 4g baking soda in the calculator and 0.789 ppm bicarbonate.

8. Pricelessbrewing QA Software Tester Staff Member

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#8
Adding acid to bicarbonate produces carbonic acid, lactic acid in particular consumes bicarbonate at 1 part acid to 1 part bicarbonate.

9. Nosybear Well-Known Member

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#9
Dependent on the pH. At 5.4, I believe around 97% of the carbonates in water are bicarbonates.

10. Nosybear Well-Known Member

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#10
But I am ready to concede I shouldn't have added it but for future, darker brews that may require increasing pH, why did the calculator show such a minute contribution from the bicarbonate?

11. Pricelessbrewing QA Software Tester Staff Member

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#11
Because there's an acid addition. At risk of oversimplifying it, you either use acid or bicarbonate to hit your desired mash pH. If you're adding both, they're counteracting each other.

Then you play with the other additions to hit your desired Ions.

12. Nosybear Well-Known Member

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#12
I still got those crazy amounts...

13. Craigerrr Well-Known Member

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#13
.

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#14
Try removing all of the misc water agents from the recipe builder (but write them down so you remember what they are- that's what I had to do). Then remove the water calc link.
Save the recipe. And then, without adding the water agents, link the water calc and add them there. You can watch the additions change your "actual", as you add them one by one. The baking soda definitely adds 85.947 ppm:

your screenshot with the "crazy" amount of bicarb is after you add the acid. So, if you go step by step, and add the acid last, you'll see that amount since the acid neutralizes the bicarbonate.

15. Pricelessbrewing QA Software Tester Staff Member

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#15

I'm at work so not able to test, but I hope that the order doesn't matter? If you add the acid then the bicarbonate you get the same result right?

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#16
Yes- that's why the 'weird' results. If the acid is in there already, adding the baking soda won't increase the HCO3 (and so you don't see the increase of 85 ppm).

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17. Nosybear Well-Known Member

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#17
Rather counterintuitive, since I am (correctly or not) adding the ion. But it also answers another question from when I was using tap water, the water alkalinity never reflected as the presence of a bicarbonate ion, I was defeating it with acid. I'll humbly offer the following suggestion: If you add an ion, you should see it in the water section and let the acid offset affect the pH... Won't be a factor in the future as I won't add bicarbonate unless I need to raise pH, just something to consider - the current behavior really threw me a curve ball!

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#18
But, the acid DOES neutralize the bicarbonate, so by showing it means it looks like it still is there, affecting the mash. And it is not.
It does show when you add it, until you add the acid which neutralizes it. That's why I did the screenshots in order to show the progression of 0 HCO3 (in the distilled water, but interestingly RO water can have up to 17 ppm), then adding NaHCO3 brings it up. Then, adding lactic acid reduces it (or neutralizes it), as in this case.