For future refence here is Brewlabs reply to my question:
Typical Liquor Analysis Required per Product
Bitter Mild Stout Lager
Calcium 170 100 100 50
Bicarbonate 25-50 50-100 100-200 <25
Chloride 200 300 300 10
Sulphate 400 150 100 10
Brewing liquor calculations
For example:
The analysis of a brewing water indicates that there are 260 degrees of alkalinity. For bitter beers the target is around 50 mg/l, so we need to reduce alkalinity by 210 mg/l, for this water type.
If the intention is to brew 5 barrels, then this equates to 5 x 164 L = 820 l
Thus 820 x 210 = 172,200 = reduction required for brewing liquor.
Reduction stated by manufacturer of sulphuric acid, at a concentration of 25% is as follows:
57 mls reduces alkalinity by 101 mg per 164 litres (1 barrel)
This equates to 57 ml reducing 101 x 164 = 16564 degrees of alkalinity
Thus, 1L will reduce 290,596 mg of alkalinity.
For a 820 litre (5 brl) brew with this water you will need to reduce 820 x 210 = 172,200
Thus 172,200 (required reduction) 290,596 (reduction /L) = 0.593 litre or 593 ml of 25% sulphuric acid required.
This should neutralise the hardness of the water and help keep the mash pH at the correct level.
Regarding the other important ions for the production of ales, the standard range for them is as follows:
The water has lower levels of these critical ions than we require so you will add both sulphate and chloride. We will use the calcium salts of these to also raise the calcium level, which is important for correct mash pH and successful yeast flocculation.
As an example: an analysis report indicates - to produce a good liquor for the production of bitter ales, the Sulphate level needs to be raised by 200 mg/l to 400 mg/l. The Chloride needs to be raised by about 114 mg/l to 200 mg/l and the Calcium level by at least 25 mg/l. Brewing liquor treatments can be purchased from Murphy and Sons / AB Vickers.
Calcium Sulphate when dissolved in the mash will provide; calcium 40 mg/l and sulphate 96mg/l for every 28 grams to 164 litres of water.
Calcium Chloride when dissolved in the mash will provide; calcium 47mg/l and chloride 84 mg/l for every 28 grams to 164 litres of water.
The calcium level needs to be in the excess so it doesn't matter if you have more calcium than the minimum 170 mg/.l
The calculations go as follows:
For a good general purpose brewing liquor for producing bitter ales:
The sulphate level in the water needs to be raised by 200 mg/l, thus (200/96) x 28 = 58g Calcium Sulphate per 164 litres; this will also provide (40 x
(58/28) = 83 mg/ l of calcium.
The chloride level in the water needs to be raised by 114mg/l, thus 114/84 = 38g Calcium Chloride per 164 litres; this will also provide (47
x 38/28) = 64 mg/l of calcium.
So the final brewing liquor would contain:
Sulphate = 200 + 200 = 300 mg /l
Chloride = 86 + 114 = 200 mg /l
Calcium = 183 + 64 + 83 = 330 mg /l
The salts MUST be added to the dry grain and NOT the hot liquor tank, as they are difficult to dissolve. All three of these key brewing ions should be at acceptable levels once the water has been treated and thus should provide a good brewing liquor, especially for light bitters. If other products are going to be produced, say milds, stouts or lagers, then the amounts and ratios of the calcium sulphate and calcium chloride can be changed to match the style.
When you are actually brewing check the pH in the incoming water, the treated water, the mash liquor, then the first worts, worts pre and post boil (cooled) and then the final fermented product. You can then compare them to the standard pH values in the table below and they should be within the normal ranges.
Part of brewing process Normal pH range
Raw liquor 6.8 - 8.0
Treated liquor 6.5 - 7.0
Mash 5.2 - 5.5
1st runnings 4.8 - 5.2
Last runnings 5.4 - 5.6
Wort pre boil 5.1 - 5.4
Wort post boil 4.9 - 5.3
Final product 3.9 - 4.2