Hey,
you just happen to be in luck that I'm currently deep in water chemistry as preparation for my masters exam this week.
First question: why are trying to replicate this water? What is your goal? Is it just to have done it? Or are you trying recreate an old Burton recipe for nostalgic reasons?
Second question: what type of beer are you trying to brew??
I've done a hand analysis of both the sydney and burton water the german-braumeister way, and in all honesty, as brewer I look at the Burton water and think "Holy crap! That's pretty salt water! Unless your brewing very dark beers that are supposed to have a harsh bitterness, this water needs some serious treatment before being able to brew a nice beer with".
Granted, this is based on the assumption of brewing soft, highly drinkable bavarian beers.
Which is why i asked what type of beer it's for....
That Sydney water is deliciously soft. The lack of Total-alkality (and subsequent negative residual alkalinity) is going to work in the favour of keeping the mash-pH not too high.
Without more detail I can't tell you exactly where it's going to be. The most accurate way is with a benchmark from known water and known malt-bill.
However, I would assume that for a beer mostly based on Pils-Malt, you'd be in a pretty good range to favour the alpha and bete amylase. Ideally, this will increase attenuation, resulting in a crisper more elegant beer.
The Ca:Mg ratio (1.9°dH : 1,6°dH) should be a bit more like 3:1, but since this is already so low, I wouldn't be massively worried about it.
In general, Mg carries the bitterness in beer a bit more pronounced.
Having said this, a bit of mineral content is also good for the yeast (just like us). However, too much is also bad (ever tried drinking seawater?)
For instance, too much Ca can lead to PYF (Premature Yeast Floculation) resulting in the yeast clumping together before she's actually finished with all the fermentables in solution, then falling to the bottom and you ending up with a "stuck" fermentation.
If it were me, brewing a darker beer with that water, I'd certainly consider upping the carbonate hardness a bit.
I just did some really quick calcs, and if you wanted, for example, to raise the carbonate hardness by 5°dH, you could add 90mg/L of CaCO3 (Note: that's MILLIGRAMS!!! Not grams!)
This will bring your total hardness up to around 10°dH (according to the official specs for brew water from Meback, that is "medium hard". Above 14°dH is "Hard". Belove 8.4°dH is "Soft")
By adding CaCO3, you'll also tip the scale a bit in the Ca:Mg ratio. For a less hoppy dark beer (e.g. bavarian Dunkles) this is good. However if you're brewing a hoppier dark beer like an english bitter or something, you could add a bit of MgSO4 to help make the bitterness a bit more pronounced and drier.
However, we're not talking about much here. Probably around the same amount per Litre as the CaCO3. (I haven't calculated this, but since they're molecolar masses aren't thaaat different, it'll be pretty close).
An idea might be to try and replicate exactly the same brew, changing only the water, and see which you like more...
