Calculating HCO3- level from other parameters.

[RandyAB]

Ok, so it's been a little while since high school chemistry so I need a little help.

I got a water profile from the town which had all of the necessary info to plug into Beersmith 2 except the HCO3-. What the report does include is two parameters which I think should allow me to calculate the appropriate number to plug in. They are:

Total Hardness (as CaCO3)=124
Total Alkalinity (as CaCO3 to pH 4.3)=80

Anybody know the bicarb level from those numbers?

Also, instead of ppm's for the other solutes such as Ca the units are expressed in mg/L. I think that is pretty much a straight conversion n'est pas?

Thanks for the help.

 

[afr0byte]

I'm sure AJ or Martin will chime in, but I believe it's usually roughly 1.21 * alkalinity...so about 96 in your case. The pH of your water will affect it a little bit, though.

 

[ajf]

Wrong AJ, but I agree with the above

-a.

 

[rancidcrabtree]

Yes, there are a million milligrams in a liter so it's a straight conversion, 1 PPM = 1 mg/L

 

[RandyAB]

Thanks guys for the great info!

 

[rancidcrabtree]

I don't know if you will be able to see the picture I attached or not, but if you can...

You can calculate your exact amount of bicarbonate alkalinity (HCO3-) using the table, if your water report shows your total amount of phenolphthalein alkalinity. Your phenolphthalein is "P" under the titration column and "T" is your total alkalinity. Kinda confusing but it works.

 

[rancidcrabtree]

I should also say, if there isn't phenolphthalein alkalinity listed on your municipal water report you probably don't have any which means your HCO3- would be equal to your total alkalinity (80 mg/L).

 

[RandyAB]

Thanks rancidcrabtree for your input. The water report did not include phenolphtalein so I'm just going by the 1.22*Alkalinity formula. I guess the water profile only becomes important if you want to emulate certain styles made with rather extreme water profiles such as Burton brewed ales. It was nice to know that our muni water is rather average.

 

[mabrungard]

Without a pH value for the water, using that 1.22 conversion is as good as it gets.

Regarding the mg/L issue. For dilute solutions, mg/L is functionally equivalent to ppm.

 

[rancidcrabtree]

Not to split hairs, because the difference between 80 and 96 isn't that big, but if you have no P alk your total HCO3 is going to be exactly 80 mg/L, the 1.22 conversion isn't necessary. Like you said, your water is average and you're not trying to brew a Burton ale so it isn't going to be a big deal at all. Happy brewing!

 

[DeafSmith]

Not to split hairs, because the difference between 80 and 96 isn't that big, but if you have no P alk your total HCO3 is going to be exactly 80 mg/L, the 1.22 conversion isn't necessary. Like you said, your water is average and you're not trying to brew a Burton ale so it isn't going to be a big deal at all. Happy brewing!

I'm just trying to get this straight in my own mind. Are you saying that HCO3 in ppm is the same as total alkalinity "as CaCO3", or do you mean HCO3 "as CaCO3" is the same as total alkalinity "as CaCO3" ? I was under the impression that the 1.22 conversion factor is because total alkalinity is typically listed "as CaCO3" and HCO3 is typically listed as ppm.