Water Chemistry - I'm Just Not Getting It

[user 197168]

Ok, so thanks to this forum, and mainly the sticky by Yooper at the top of the page, I've gotten into water chemistry. Here in Sydney we have fairly soft water so initially I followed the guide and did the 2% sauermalz and teaspoon of calcium chloride. It seemed to work fairly well.

Then, I caught the water tweaking bug and downloaded EZ water calculator. It was here I noticed my calcium and magnesium numbers were under the recommended range so I started adding epsom salts and gypsum as well. While doing this I was keeping an eye on my chloride to sulphate ratio and adjusting as needed.

Anyhow, an already long story short, I now think I've gone too far. It seems my last few beers are a bit weird tasting. Not terrible, but odd. The IPA I brewed recently seemed very nice in the fermenter, but now it is REALLY bitter. My chloride to sulphate ratio was 0.41, which I knew would enhance bitterness, but I didn't think it would be by this much.

I then read John Palmer's notes on residual alkalinity, which is also included in EZ water calculator (albeit very small), and I really don't get it. I understand the calcium and the magnesium play a part, and I understand that dark malts also play a part, but to me RA seems to be the result of the equation, and then we are trying to work out the parts of the equation from the result.

So if I am adding acidulated malt, surely the alkalinity of my water would drop, would it not?

Anyhow, feel free to forum slap me and tell me to go back to kit beers. Or tell me what I'm missing. Thanks!

 

[Ryush806]

The residual alkalinity IS the result of a big nasty equation. Basically it calculates the effective alkalinity (essentially your carbonates, bicarbonates, and your hydroxides minus your acidulated malt and your lactic acid) and then using some conversions it subtracts the calcium and magnesium levels to get to residual alkalinity. The residual alkalinity is then combined with all the different malts that you use and calculates a predicted pH of your mash. Different malts counteract the residual alkalinity by differing amounts blah blah blah math = pH!

As far as your odd tasting IPA goes, is it a minerally taste? That would indicate too much sulfate (regardless of the chloride/sulfate ratio). Is it kinda sour or maybe sharp? That could be too low a mash pH. Have you had your water tested to get the ion profile (I assume you have since you've been using EZ water). When was the last time you did it? If it's been a while the water may have changed and could cause your pH calcs to be off.

 

[user 197168]

Thanks Ryush. I'm sort of following now. It still seems quite counter-intuitive though. I mean, it seems more natural to design your beer then adjust your water to suit. Not the other way round. (Or maybe I'm still not following).

As far as my IPA goes, it was kinda high in sulfate at 214ppm, but I thought that was in range. It IS kinda sour, but more bitter I would say, and it finishes very dry. Like I said, it's not nasty or even crazy bad, just a bit odd.

The water report is just from the water supply website, but it is fairly comprehensive. I haven't invested in a ph meter yet, so I can't definitively say it wasn't a low mash ph. I guess I should invest.

 

[ajdelange]

I understand the calcium and the magnesium play a part, and I understand that dark malts also play a part, but to me RA seems to be the result of the equation, and then we are trying to work out the parts of the equation from the result.

So if I am adding acidulated malt, surely the alkalinity of my water would drop, would it not?

Assuming that the goal of water treatment (which is really water plus mash treatment) is to get the mash pH right then the job involves tracking protons (hydrogen ions). Some things in the system such as the bicarbonate ions in the water (which are the source of most of the water's alkalinity under normal circumstances) and base malts absorb protons and some, such as added acids, sauermalz and high kilned malts, give them up. The extent to which protons are absorbed or given up by any of the mash components depends on the pH. Mash pH settles in at the value where the sum of the absorbed protons is just equal to the protons given up.

When calcium and magnesium in the water encounter phosphates from the malt they give up some protons and these must be included in the balance equation. This is what RA is all about. Each equivalent of calcium gives up 1/3.5 equivalent of protons and each of magnesium half that number. The RA calculation takes into account the extent to which these protons offset the alkalinity (bicarbonate) of the water. Thus
RA = alkalinity -(calcium - 0.5*magnesium)/3.5
This is intended to be a measure for characterizing and comparing sources of brewing water, not mashes, but many of the spreadsheets in common use try to extend the concept to the mash and this confuses lots of people. Theoretically it is quite OK. RA is just one part of the system proton deficit. If you add sauermalz to a mash that offsets the alkalinity of the water and so you can write

proton_deficit = proton_deficit_other_malts + RA - proton_surfeit_sauermalz

or you can roll the proton surfeit of sauermalz into RA. Here's where the confusion comes in.

Until spreadsheets start tabulating the individual proton deficits and surfeits of mash components (this isn't likely to happen soon - the concept was cooked up for the Palmer book and not published in all its glory until the last issue of MBAA TQ) it is probably best to ignore the RA field in spreadsheets and focus on the estimated mash pH field.

 

[Ryush806]

Thanks Ryush. I'm sort of following now. It still seems quite counter-intuitive though. I mean, it seems more natural to design your beer then adjust your water to suit. Not the other way round. (Or maybe I'm still not following).

As far as my IPA goes, it was kinda high in sulfate at 214ppm, but I thought that was in range. It IS kinda sour, but more bitter I would say, and it finishes very dry. Like I said, it's not nasty or even crazy bad, just a bit odd.

The water report is just from the water supply website, but it is fairly comprehensive. I haven't invested in a ph meter yet, so I can't definitively say it wasn't a low mash ph. I guess I should invest.

I usually get my recipe set and then play with my water. Like ajdelange said, don't worry about that RA field too much and just use the mash pH.

Also buy that pH meter NOW!! You can hope and pray that EZ Water gave you all the info you need and you built the proper water profile to give you the right pH...or you can know for sure. I have had instances where my mash pH ended up a decent amount higher or lower for whatever reason. Could be the malts had something different than normal. Could be the water supply source turned over and kicked up some weird stuff. Could be I'm a moron and didn't measure out the correct amount of salts. The thing about the pH meter is that you know your pH and can add some lactic acid or some lime to pull it back to the proper range.

 

[user 197168]

Cheers AJDelange! I took some time to read your post to make sure it all sank in. I think I now get it. Thanks!

Ryush - Yep, a pH meter is definitely on the cards. It would be good to be sure what is going on.