Why does water volume matter when determining minerals to add?

I am confused about something - from what I have read, one treats the entire water volume with minerals, rather than treating the final volume.


1. Other than for Ph affecting the mash properties, can one not simply add the correct amount of minerals for say 5.5 gallons (batch size + loss) at the start of the boil? Aside from the slight Ph drop, isn't the purpose of the minerals to affect taste, so it wont matter if they are added after the mash?


2. Lets say I do Brew in a Bag (BIAB) with 8 gallons of water, expecting 1 gallon of loss in the grain and a final volume of 5.5 gallons (some of which will be lost in the dead space). From what I have read, one should treat 7 gallons of water, instead of 5.5 gallons of water? Why?
Wont you end up with concentrated minerals, as the 7 gallons gets boiled down to 5.5? (1 gallon will remain trapped in the grain)


3. If you have a wider and shorter brew kettle, with a higher evaporation rate, you will need more water. If the add extra minerals for that additional water, than you will end up with a more concentrated mineral amount in your final wort volume. It doesn't seem correct that you use different amounts of minerals for different dimension kettles (though one has a bit more water) does it?

I think you need to first ask yourself exactly why you're treating the water. Those minerals, from what I understand, are typically added to assist with the mashing process, aren't they? If that's the case, wouldn't you necessarily have to treat the full volume you mash and, by extension, sparge, with?

And why would you exclude the amount of water absorbed by the grain? That one's kind of got me.

>>I think you need to first ask yourself exactly why you're treating the water. Those minerals, from what I understand, are typically added to assist with the mashing process, aren't they?

I don't think thats true, except maybe to lower the Ph a little.


>>And why would you exclude the amount of water absorbed by the grain? That one's kind of got me.

If you add the salts after the mash.
Otherwise you would have to factor in the water retained in the grain. But it gets a bit more complex, as you don't treat 1 more gallon, you need to scale up by a percentage based on the water retention volume compared to the overall volume.
So if 1 gallon is retained, and 7 gallons will remain, then 1/8 more salts will be needed.
Is that correct? If not, why?

ArcLight said:

I am confused about something - from what I have read, one treats the entire water volume with minerals, rather than treating the final volume.


1. Other than for Ph affecting the mash properties, can one not simply add the correct amount of minerals for say 5.5 gallons (batch size + loss) at the start of the boil? Aside from the slight Ph drop, isn't the purpose of the minerals to affect taste, so it wont matter if they are added after the mash?

Click to expand...

You will end up with less minerals in your 5.5 gallons as some will be "trapped" in the trub.

ArcLight said:

2. Lets say I do Brew in a Bag (BIAB) with 8 gallons of water, expecting 1 gallon of loss in the grain and a final volume of 5.5 gallons (some of which will be lost in the dead space). From what I have read, one should treat 7 gallons of water, instead of 5.5 gallons of water? Why?
Wont you end up with concentrated minerals, as the 7 gallons gets boiled down to 5.5? (1 gallon will remain trapped in the grain)

Click to expand...

To the extent you lose liquid to evaporation, you will have a greater concentration of minerals in your 5.5 gallons as minerals don't evaporate.

ArcLight said:

3. If you have a wider and shorter brew kettle, with a higher evaporation rate, you will need more water. If the add extra minerals for that additional water, than you will end up with a more concentrated mineral amount in your final wort volume. It doesn't seem correct that you use different amounts of minerals for different dimension kettles (though one has a bit more water) does it?

Click to expand...

Yes, it does for the very reason you mentioned. Different kettle geometry results in different evaporation rates, and hence mineral concentrations.

Most home brewers don't tune for a particular mineral content in the beer. Most tune for brewing water that gives them a good beer. Thus we tweak calcium and acid additions to give us proper mash pH and sulfate and chloride additions to give us the flavors we like in the finished beer. Losses to grain and boil have no effect on mash pH because the grain is soaking in the mash water and water lost in the boil happens after the mash is completer. Losses to grain and boil do have an effect on the stylistic ions' concentrations in the final beer. If one uses a fixed amount of salts containing these and then changes his boil such that he loses 20% of his water rather than 10% then clearly the concentrations of these salts will be higher. Unless, of course, he makes up for the water lost with low ion content water (this is what I do). If he doesn't do that then the change will either improve or detriment his beer. If it detriments it the brewer will simply add less of the offending ion when he prepares his mash water for the next brewing session.

>. If it detriments it the brewer will simply add less of the offending ion when he prepares his mash water for the next brewing session.

Ok, this is what I was after. Thank you for the answer AJ.

What I will do is calculate the 5.5 gallon amount, scale up for the loss to grain and try that.
It will be less than the normal amount for the full water, but I think the overall taste will be good.
And as you say, its an iterative and experimental process.