Water Treatment Using CRS & DLS

[user 6402]

I have decided to start using CRS & DLS again. I used to use them many, many years ago but stopped for whatever reason I can't remeber. There is something on the Brupaks info on these products I find confusing, if not misleading.
Firstly, I have obtained a water analysis report from Essex & Suffolk water. I am fortunate that they have supplied both Hardness as CaCO3 mg/l, and alkalinity as HCO3 mg/l.
CaCO3 - 266.72
HCO3 - 205.00
I have also purchased a Salifert KA/Alk Profi test kit, which I have still to use.
Going back to the Brupaks info, quote "Water authorities usually express alkalinity as HCO3 (hydrogen carbonate) whereas the brewing industry uses the traditional CaC03 (calcium carbonate). To use the tables below you will need to know the alkalinity expressed as CaC03. As you will probably have only the HC03 value, you can convert it to CaC03 simply by dividing this figure by 1.22." Following their instructions, if I divide the HCO3 value by 1.22 I get 168.03, nowhere near the quoted figure of 266.72. If however I MULTIPLY the HCO3 value by 1.22 I get 250.1, a lot closer to 266.72. Is the Brupaks info wrong or am I misreading something?
.

 

[user 6402]

I have just read over my own message posted 15 minutes ago. I realise where I have got it wrong. I am confusing the Hardness figure expressed as CaCO3 with the Alkalinity figure expressed as HCO3.
Hardness as CaCO3 - 266.72
Alkalinity as HCO3 - 205
Using Brupaks info, the Alkalinity expressed as CaCO3 is 168.03. Is this the figure to use when I want to adjust the Alkalinity?

 

[Mayor of Simpleton]

Yes. To convert from alkalinity as bicarbonate (HCO3) to calcium carbonate (CaCO3) you divide by 61 and multiply by 50. I think the confusion is coming from the fact that hardness and alkalinity can both be measured as equivalent weights of CaCO3 but they aren't measuring the same thing.

 

[user 6402]

Yes. To convert from alkalinity as bicarbonate (HCO3) to calcium carbonate (CaCO3) you divide by 61 and multiply by 50. I think the confusion is coming from the fact that hardness and alkalinity can both be measured as equivalent weights of CaCO3 but they aren't measuring the same thing.

Cheers Mayor, I think I've finally got my head round the way the figures are expressed as.