Water chemistry calculation confusion - "mash water volume".

[Joe DS]

Hi all, I'm onto my second all grain batch (this time a Beavertown Gamma Ray clone).
To improve my water chemistry, I've got gypsum and Carbonate Reducing Solution (CRS) (as well as campden tablets).

Attached I've inputted my source water profile, desired style (APA) etc. but am getting confused on the volume to put under "mash water volume (L)". The batch I am aiming for is 11L, and my understanding is that the concentrations of added salts like gyspum should be calculated on the target batch volume (11L), and not the "mash water volume" which would be more (say 14L). In other words, if I enter 14L as the mash water volume, the output salt concentrations will be stronger than intended as it doesn't account for evaporation of the 14L to 11L.
The mash water volume has a great impact on the output amount of CRS (and change in alkalinity) and I don't want to end up adding too much acid and messing up the beer entirely.

I'm also aware that the calculator I'm using lists "10% Sulfuric" whereas I believe CRS is listed on the bottle as "Sulphuric Acid <15%" - on Malt Miller there is a table that lists Alkalinity Reduction against volume of CRS, so I will use this to match the CRS volume against the "Alkalinity Reduced (as CaCO3)" as listed in the excel sheet.

I hope this makes sense - I would really appreciate your thoughts and a glance over the attached calculator to make sure I am on the right track.

Thanks

 

[strange-steve]

my understanding is that the concentrations of added salts like gyspum should be calculated on the target batch volume (11L), and not the "mash water volume" which would be more (say 14L)

No you should use the volume of the mash water being treated (and sparge water if using) rather than the finished batch size.

if I enter 14L as the mash water volume, the output salt concentrations will be stronger than intended as it doesn't account for evaporation of the 14L to 11L.

Technically yes you're right, however there are other factors to consider. Firstly, the volume loss from mash water to finished volume (14L to 11L in your example) isn't down to evaporation alone, there's also grain absorption, mash tun dead space, loss due to boiler trub, hop absorption etc. Evaporation during the boil will cause some concentration of mineral content however the evaporation rate is usually around 10% per hour (give or take a few percent). That means the actual difference in concentration of a particular ion after a 1hr boil is about 11%, which isn't that much really, especially when you consider just how inaccurately we know the starting concentrations, how inaccurate our additions are, and also that we have no real idea of what quantity of the initial ions in the water are still there after the mash. You can see that worrying about a few ppm either way is pretty pointless

The mash water volume has a great impact on the output amount of CRS (and change in alkalinity) and I don't want to end up adding too much acid and messing up the beer entirely.

Again use the water volume, not the batch size because it's specifically the alkalinity of the water that you want to adjust. We don't talk about wort alkalinity because it doesn't really mean anything, the alkalinity of the post boil wort will be zero.

I'm also aware that the calculator I'm using lists "10% Sulfuric" whereas I believe CRS is listed on the bottle as "Sulphuric Acid <15%"

Yes but CRS also contains hydrochloric acid.

on Malt Miller there is a table that lists Alkalinity Reduction against volume of CRS, so I will use this to match the CRS volume against the "Alkalinity Reduced (as CaCO3)" as listed in the excel sheet.

That's probably a good idea

 

[Joe DS]

Thanks a lot strange-steve! I've read your beginners guide to water treatment which is brilliant.
Regarding getting the alkalinity right, is CRS the best product to use? I realise it raises the sulphate levels and I can see there is a "sulfate to chloride ratio" measure in the above excel calculator - do I need to be worried that both gyspum and CRS will raise the sulphate levels too high? I use gypsum as I brew hop heavy beers like NEIPAs.

Any other tips on water chemistry would be greatly appreciated.