Reading water report - Alkalinity/Hardness CaCO3

[MrN]

I've started playing with water chemistry in my brews. I can get a water report online from my supplier (sout east water) and it says "The water hardness for your property is 310mg/l CaCO₃". I've been using this figure on calculators like the brewer's friend mash chemistry one where it asks for Alkalinity ppm as CaCO3 however I've now read that hardness as CaCO3 is different to alkalinity as CaCO3. Is this correct and am I using the wrong figure in my calculations? If so is there a way to calculate the alkalinity?

[MTW]

You will get a fuller reply than mine imminently, but your alkalinity expressed as ppm CaCO3 is likely to be roughly twice the calcium figure, though usual warnings about those being historical figures and averages apply. I measure mine with a Salifert kit on brew day.

[MrN]

Interesting thanks, that would make it more like 237ppm. I'd been thinking about getting one of those kits, it'd be interesting to see how far off I might have been.

[Eric]

Water hardness is, in practical terms, a measurement of the amount of calcium and magnesium of every form found in water. One way of expressing the quantity is the amount of calcium carbonate in solution that would produce an equivalent amount of hardness.
Some part of that hardness will be the form of alkalinity, also frequently expressed as the amount of calcium carbonate to produce an equivalent amount of alkalinty.
Alkalinity should always measure less than hardness. A kit to measure alkalinity can be an essential piece of equipment for brewing with highly alkaline water or one that can vary significantly with time.

[MrN]

Thanks, that's very informative.

One thing I'd been doing was combining with the Asda Eden Falls water which is meant to have a relatively low amount of bicarbonate - about 30mg I think.

[Eric]

Thanks, that's very informative.

One thing I'd been doing was combining with the Asda Eden Falls water which is meant to have a relatively low amount of bicarbonate - about 30mg I think.

It's easier, quicker and cheaper to use acid. A Salifert test will confirm the treatment and cost will be offset adding less calcium salts. Of course that will exclude producing certain profiles, but the best way to appreciate the advantages water treatment is to ensure there's sufficient calcium at every stage. A crisp clear decent pint in a fortnight gives me more satisfaction than getting a specific reading on a pH meter in a sample of wort from the mash.

[MrN]

Good point, I'll try and get my hands on one of those test kits. I have some CRS which I've also used, is there any reason I might want to use something else like lactic acid? The brewer's friend calculator is the only one that seems to include CRS as an option.

The report averaged my calcium as being 118.5 mg/l which I believe is reasonable? I have also experimented with a bit of gypsum and epsom salts. How do you decide whether to add salts to mash or boil, out of interest?

[Eric]

Waters like yours and mine are not suited for lactic aid which brings with it a taste. The amount of alkalinity requires a similarly large quantity of acid and while small quantities of lactic acid can impart a beneficial flavour in some beer styles, not at such high levels.

Graham Wheeler's Water Treatment Calculator uses CRS and is available via the Extras tab at the top of the page or direct.

Calcium additions to mash or boil? A subject worthy of much discussion.
Calcium is by far the most important ion in brewing. You can brew without it in your liquor, malt comes with a supply, but such beer will need time and/or treatment to clear and taste at its best. Calcium is essential at every stage and when used in one is usually deposited there and won't be available for other reactions or in later stages. It is possible to think the mash has sufficient salts for all stages but can find that not enough reaches the kettle to form good hot break. In today's brew half my salt additions went into the mash, a quarter were added to the grainbed halfway through the sparge and the rest to the kettle. This method seems to improve sparge efficiency compared with fly sparging without those salts, but it's early days yet.