Temporary Hardness in Wort Boil

[TameTurkey]

I listened to (& really enjoyed) the WaterGanza series on Brew Strong, but I'm still confused on one point. I understand that temporary hardness of water can be largely removed by boiling, so doesn't that also mean that temporary hardness would be largely removed during the boil of the wort? For example, if my water has temporary hardness (or if I added chalk to the mash), wouldn't I expect calcium carbonate precipitate to form during the wort boil? As a result, wouldn't my calcium concentration go down as a result of the removal of temporary hardness during the wort boil?

[alanzo]

I listened to (& really enjoyed) the WaterGanza series on Brew Strong, but I'm still confused on one point. I understand that temporary hardness of water can be largely removed by boiling, so doesn't that also mean that temporary hardness would be largely removed during the boil of the wort? For example, if my water has temporary hardness (or if I added chalk to the mash), wouldn't I expect calcium carbonate precipitate to form during the wort boil? As a result, wouldn't my calcium concentration go down as a result of the removal of temporary hardness during the wort boil?

You may be thinking about this too much. AFAIK, no one boils their brewing liquier to remove hardness. If it's really an issue, brewers either go 100% Reverse Osmosis water, or cut their tap water 50:50 (or whatever works) with Reverse Osmosis water.

But in direct response to your question, personally, I have no clue.

[TameTurkey]

I'm wondering about unintended removal of calcium during the wort boil due to the calcium carbonate dropping out of solution. For example, let's say that I use only distilled water from the very beginning. I add chalk to the mash to achieve a certain RA. That's adding temporary hardness to the mash water. But, the chalk also added Ca to the brewing water. After I sparge, I can calculate a certain amount of Ca in the pre-boil wort that is due to the chalk that I added to the mash. Now, when I boil the wort, wouldn't that temporary hardness (chalk) simply be removed by dropping out as a precipitate? So, the Ca contribution that I made back at the mash would simply be removed during the wort boil (unintentionly)? Thanks!

[Quin]

You will also pick up a lot of minerals from the malt itself. Also I wouldn't expect any of these reactions to go to completion, so you're not going to precipitate all of the calcium.

[spiderwrangler]

You drop Ca from precipitates with phosphate too, but I don't think you need to overcompensate for these perceived losses. As far as I'm aware, the desired Ca levels are for brewing water, not for finished beer, so losses are expected, since Ca is playing a big role in keeping things in line during the mash.