Ran an experiment to compare the effect different levels of mash Ca, 6ppm, 49ppm and 367ppm has on post boil wort taste and appearance.
Tap water (from water report):
250g Crisp Clear Choice Pale Malt
750ml mash water
2L sparge water
40min mash, sparged using sieve (no vorlauf), 10m boil
10m cool (no chiller)
ppm calculations via Brewfather.
A. No salts
Post sparge colour look dull yellow and had brown foam and tasted harsh.
Post boil Wort tasted harsh and foam was darker brown. It's opaque, what looks like the base of the pot is a shadow.
B. 0.05g Gypsum. 0.05g Calcium Chloride
Mash
Wort
post sparge photo missing but looked similar to C (no brown foam).
Post boil looks slightly bright, e.g. can see a tiny bit of metal shine coming through. No hot break. Tasted slightly harsh but foam wasn't brown (same at preboil).
C. 0.5g Gypsum. 0.5g Calcium Chloride
Mash
Ca | Mg | Na | Cl | SO | HCO |
367 | 1 | 4 | 350 | 406 | 20 |
Wort
Post sparge was nice cloudy yellow with white foam.
Wort tasted fresh and looked very bright. White foam. Visible hot break.
Conclusion
C looks and tasted best. Maybe B just needed a touch more Ca to fix its harsh taste since it didn't have the brown foam problem. It would be interesting to know what level of Ca gives the dramatic protein precipitation (or hot break?) post boil.
Regarding pH: Sorry this is not scientific! A and C had no pH adjustment and wasn't measured. B mash pH was a bit high at 5.8 so a drop of lactic was added which lowered it to 5.4, a microscopic amount of lactic was added to B's sparge taking it from 8 to 5. B post boil was 5.2.
Future Work
I could run the experiment again with say 200ppm Ca in mash water if anyone is interested to see how it compares to C. That would be 0.27g each of Gypsum, CaCl.
Also if we are supposed to have 50ppm in both the mash and sparge water then that would actually be 0.05g (each salt) in mash water and 0.17g (each salt) in the sparge water. It would be interesting to see what the post boil wort compares to B.