Most all grain suppliers will have a range of Salts available, Brewman is my local so I get what I need there and don't pay too much attention to what other shops offer, that's something you will need to explore for yourself.
The most common salts are Calcium Sulphate (gypsum), Calcium Chloride and Magnesium Sulphate (Epsom Salts)
These are used in varying ratios to get-
1/ the right amount of Ca in your water, you need 50-100ppm (same as mg/L) at a minimum.
Ca is important to lower the pH (come back to that) helps protect enzymes from heat in the mash (especially Alpha Amylase) helps form flock in the kettle, its a nutrient for yeast and helps yeast to flock at the end of the ferment and more minor effects.
2/ To affect the taste of the beer, Sulphate makes the hops more pronounced (in your face) up to a point where it makes the hop taste harsher. Chloride mellows the flavour, gives a softer and rounder beer. A balance of the two is often used to get the flavour you want. Typically beer styles evolved in response to the mineral profile of the water the brewer had available. Remember brewers have been taking steps to modify their water for hundreds of years so what comes out of a tap in Munich (for instance) might not have much to do with what the local brewery is using.
Best to learn what salts do and build the water you want.
3/ Lower the pH, Your water is pretty close to 7pH (neutral) (7.5-8pH), Calcium in the water reacts with Phosphates in the malt and forms Calcium Phosphate which is pretty much insoluble so it falls out in the mash and leaves a bunch of Hydrogen ions in solutions H ions are pretty much what pH is, so more makes the pH lower and gets you closer to the ideal pH for mashing and the following processes.
The obvious limiting factor is the amount of available Phosphate, not all of what is in the malt goes into solution instantly, some doesn't react until the boil, which is one of the reasons the pH falls during the boil.
There is rarely enough Phosphate available to lower the pH far enough. If your water has a lot of Carbonate that would need to be neutralised first, so we mostly need to add some acid.
I prefer Lactic Acid, if you look at the naturally occuring acidity in pale malt about 90% of it comes from Lactic acid producing bacteria on the malt, so if you use lactic, you are adding a bit more of somethin that is already there. Phosphoric is also popular and some big brewers use Sulphuric and Hydrochloric, both of which are pretty nasty and dangerous, best avoided for home brewers.
Magnesium Sulphate is used by some brewers, personally I don't, anything Magnesium can do Ca can do better, get a bit too heavy handed with the MgSO4 and its a pretty potent laxative, it takes at least 4 times the Mg to do the job Ca does.
I mentioned Calcium Lactate above. I work out how much Sulphate and Chloride I want, then add CaLac to get the amount of Ca I want without affecting the flavour profile. There is a very powerful buffering reaction between CaLac and Lactic Acid, once you nail the pH you want it wont budge!
Water chemistry can be a bit of a rabbit hole (in the Allice in... sense), you can do the basics (make sure you have enough Ca, a fair balance of Cl and SO4, adjust the pH) or you can get lost in wonderland and not get home from there.
Do a bit of reading,
Braukaiser covers the subject very well, there is some great reading on
Bru'n Water
As far as I know
Brewman is the only HBS in Australia that sells Calcium Lactate along with all the other salts you will need. Thank God for Post packs you must be used to getting wounded on freight, but the west coast is a bit of a black hole for shipping stuff.
If you really care get a decent pH meter (some fair ones for well under $50, had a play with the Kegland one, not too bad for the money)
Get some CaCl and CaSO4, an acid, maybe some calcium lactate, do a bunch of reading, ask lots of questions.
Take water seriously, but not too seriously.
Lots of luck,
Mark
Oh - on Zn, its a micro nutrient and an enzyme cofactor, the best thing to do is make a stock solution say 10g/L then with a pretty basic measuring cylinder (I use a 250mL one as an hydrometer jar) just add whatever you need. Too much is toxic to yeast, too little and enzymes don't work properly, do your own reading up on Zn before you get too heavy handed. Sort of like really good chilly sauce, a bit adds, too much and the arse falls out.
M
