Advice on first-time water treatment

[tudou]

Never done this before, so was looking for some guidance from you wise sages.

Parameters are as follows (all ppm or mg/L):

Calcium: 17.2 <-Quoted from this forum by a member for Mannofield East (NE Scotland) 2003
Magnesium: ? <-Scottish water said they no longer record this as it was so stable; the gent on the phone said he would try to look it out for me but I'm not hopeful!
Sodium: 5.75
Sulphate: 15.078
Chloride: 11.778

Alkalinity: ~38 (Measured from my API hardness test kit for my aquarium)
Hardness: ~53 (API test kit again) / 42.9 (same as calcium)

Now I have stuck these into GW's calculator and a few other spreadsheet calculators. my main two questions are:

1. Given the parameters above, does anything stand out or is there some general advice you can give?

2. How do I decide how much of each salt to add? I know I should add enough to bring my pH down to about 5.2-5.4, but does it really matter which salt I add to achieve this? I suspect the answer is "yes" but I don't know why

3. I'm not sure if the API test kits are measuring as CaCO3, HCO3 or CO3 - I would have thought GH (General Hardness) is CaCO3 but then I'm not sure what the KH (Karbonate Hardness, ja?) is a measure of - just CO3?

Thanks guys

[Eric]

Some science and a lot of opinion, apply a few rules and go your own way.

1. The alkalinity is slightly high of ideal for pale beers, probably ideal for something like a brown ale and a bit low for dark beers. About 1 ml CRS for every 10 litres of liquor would reduce that alkalinity for a pale ale but to be quite frank, I'm unsure if you should bother at this stage.

2. You'll probably want to start with an absolute minimum of 50 mg/l (ppm) calcium in your water, but 100 would be better. You have 17.2 mg/l calcium already, so let's say you need another 80 mg/l. Now calcium sulphate has a molecular weight of 136 (look at a periodic table and add weights of Ca, S and 4 x O (CaSO4)) and calcium's atomic weight is 40, so, if you added 0.136 gm of CaSO4 into 1 litre (1 kg) of water then it's calcium content would increase by 0.040 gm/l, or 40 mg/l. As we need 80 mg/l we need to double the amount of calcium sulphate, so 0.272 gm per litre would raise your calcium content to 97.2 mg/l and the sulphate content by 261 to a total of 276 mg/l. Similarly you would need 0.222 gm/l of calcium chloride to give a similar quantity of calcium in your water and that would increase the chloride level to 154 mg/l.
Chloride will enhance maltiness, sulphate favours hops, you choose the balance. There are other salts to consider, including sodium chloride, but those two are enough for a start.

3. It is probable both measurements will be in CaCO3. It won't be CaCO3 in either case, just that whatever it is you have just measured in your water has an effect similar to what that amount of CaCO3 would do. Calcium carbonate isn't even soluble in water, but it is a good to use because it's molecular weight is 100 and therefore calcium constitutes 40% of its mass, making calculations easier if you add acid, although some of that supposed calcium is magnesium.

Good luck.