Help calculating HCO3 levels

[DarrenSL]

Hi

My water report (United Utilities - Watergrove Reservoir) doesn't show HCO3 content. It does however show Hardness @ 17mg Ca/L (described as 'very soft') and pH 7.1.

All other main ions are reported as:
Ca 9ppm
Mg 4.8ppm
Na 13ppm
SO4 48.6ppm
Cl 6.8ppm

From the hardness figure provided I am deriving the HCO3 content as 52ppm (based on molecular mass of Ca(HCO3)2 of 162, 17x122/40). This seems high for rain water, twice as high as Tescos Ashbeck water!

Also, when I put this level into the ProMash water profiler it estimates the pH as 8.3.

Have I missed something?

Thanks

[Charles1968]

Does the report have a figure for alkalinity? That's the one you want. Bicarbonate = alkalinity ÷ 0.83.

Hardness is usually reported "as" calcium carbonate, meaning it isn't the same as a measure of calcium carbonate as it includes other compounds. It's massively confusing.

You're lucky to have calcium and magnesium levels. If the report doesn't include alkalinity, you can measure it by ordering a salifert alkalinity test kit online.

Your calcium is very low - you'll probably need to add calcium in some form to your brewing water.

[killer]

Hi Darren,

Welcome to Jim's. First post a water chemistry question - that's hardcore !

In fact, your water numbers are a little funny looking. You have too many negative ions for it to balance - and that's before adding HCO3.
Your own calculation would be correct if you were only considering Calcium hardness as coming from Ca(HCO3)2 but equally it could come from say, CaSO4 - and your SO4 value is relatively high suggesting that your HCO3 value is low - lower than the 52 you are calculating.

Of course all this is guesswork from a water company's probably yearly average values....

You could do a couple of things - get your water tested professionally or get yourself a salifert kit which will allow you to test your waters alkalinity for relatively small money.

[DarrenSL]

Thanks for the quick replies

Makes sense now, high sulphate low carbonate in the hardness calc. And, the values are annual averages with samples varying by +-20% or more. I'll definitely get myself a Salifert kit.

I have been adding 5g Gypsum & 2.5g CaCl2 to my water for the beers I've made so far (mostly APAs & IPAs - 23L). Got a Budvar clone to do next though which will be interesting. My water profile is similar to Pilsen water except for the high sulphates. I will need a maltier profile so will just go with CaCl2 additions for that I think.

It is my first post but I've been following this forum (and other forums + brewing books + youtube channels etc) for months. In fact, I'm totally addicted to home brewing!!

Great forum btw


Thanks