Decarbonation by boiling

[Ckilner]

I've done some reading and researching on this and have also picked up some good information from other threads. Can anyone confirm my calculations?

I have water which is as follows:
Ca = 155 mg/l
CaCO3 = 389 mg/l so multiplying by 1.22 gives HCO3 = 475 mg/l

If I boil and splash the water then CO2 is released and the CaCO3 drops out so this reduces the bicarbonate concentration and also reduces the calcium.
I understand that the best I can expect is that the bicarbonate reduces to 80 mg/l which gives a CaCO3 value of 65 mg/l
The calcium is also reduced so using the formula:
Calciumend(ppm)=Calciumstart(ppm)-((HCO3start(ppm) - HCO3end(ppm))/3.05)

so in my example:
Calciumend(ppm) = 155-((475-80)/3.05) gives a new calcium value of 25 mg/l

Am I anywhere near the mark?

 

[TSMill]

Assuming the Ca and CaCO3 values are as per water report then yes, because the values suggest all calcium is present as temporary hardness. If you inferred the CaCO3 concentration based on molar masses, then perhaps not.

 

[mabrungard]

I see that you are using my information correctly. Yes, given the lower limit for calcium in the 12 to 20 ppm range, it does appear reasonable that you should be able to decarbonate that water to around 70 to 80 ppm bicarbonate. It will take at least 15 minutes of boiling to get the reaction to proceed fully. I suggest that you enlist an alkalinity test kit to check and evaluate your decarbonation efficiency. With periodic checks of alkalinity, you should be able to assess how long you will need to boil.

Be sure to decant the clarified water off the sediment to avoid redissolving the chalk.

 

[Ckilner]

Yes, many thanks Martin for your really good article/website on decarbonation and all things water. I've been studying it in minute detail and now feel like I'm getting a lot closer to understanding it and looking forward to putting it into practise on my next brew in a day or two. I have a Hanna pH meter so I will keep an eye on the alkalinity with that.

BTW. A really good water treatment calculator too. Cheers

 

[Ckilner]

How long should the water be allowed to settle after the 15 minute boil?

 

[mabrungard]

How long should the water be allowed to settle after the 15 minute boil?

Until the water clears.

A helpful technique for increasing the speed of clarification is to add powdered chalk to the boil. It sounds counter-intuitive, but what happens is that you are adding nucleation sites that improve the flocculation of the micro-particles of chalk that are precipitated by the boiling. All the added chalk and precipitated chalk will deposit more quickly on the kettle bottom.

 

[Ckilner]

Yes thanks, I read that in your article so I've added a teaspoon of precipated chalk to the 30 litre boil.

 

[Ckilner]

Finished the boil and there was certainly a lot of chalk at the bottom but was that the chalk I put in or was it added to by the water I wonder.
The pH before the boil was 7.5 and it's now 7.4. Does that mean nothing has happened?

 

[TSMill]

Hard to say, the boil drives off CO2 (which lowers pH). Carbonate and C02 act in tandem as a buffer system, more of one allows more of the other to enter solution. I think the real test will be how it acts in the mash.

 

[Ckilner]

I'm not sure what's going - quite confused as I assumed the pH should fall after the boil.
I've just run another test and boiled a smaller volume of water with a dash of chalk and got a good boil rate for 15 mins. Having let the chalk settle until the water is clear and measured the pH it's actually gone up from 7.5 to 8.0
Is this to be expected?

 

[TSMill]

My previous comment was vague, CO2 lowers pH, boiling drives it off hence rise in pH. It's buffering capacity that is important, not so much pre mash water pH.

 

[Ckilner]

OK, thanks. I'll see what happens at brew time. If all has gone according to plan I should see the correct pH of 5.4(ish) when I've added the grain and into the mash for 15 mins.

 

[Ckilner]

Very impressed with Martin Brungard's water adjustment spreadsheet! I calculated the additions I needed to bring the pH to the correct value and applied them to my latest brew.
Pre decarbonation: 7.4. pH
Post decarbonation boil: 8.1 pH
Post water treatement: 6.4 Ph
Mash: 5.5 pH

Mash pH is exactly as the spreadsheet calculated.

Looking forward to drinking this one.

 

[manticle]

Good stuff. Glad it's working for you.

To my eye the brun water info is really comprehensive and well explained. I have not used his spreadsheet but I would expect similar.

I have used the much easier ez-water calculator but intend to start looking at brun stuff and comparing some time in the near future as it seems more complex but possibly with better/more accurate results. For me with soft water, close enough is often good enough but I'm interested in the topic and may not always have the same water source.

 

[Byran]

I was in Alice springs a while back and as they use the Great Artesian Basin for their water supply they seem to get a great deal of calcium buildup on everything the water touches. I think this practice would be very useful to anyone in those parts of Australia that needs to reduce it for brewing.
My uncle always complains about the taps getting clogged with calcium and ****.

 

[Ckilner]

Very hard water here and my taps are the same. Every so often I have to chip the calcium away from the tap outlet. Everything is always covered in scale but apparently hard water is good for brewing (not that i'm an expert - this is my first water adjusted brew )

 

[Byran]

Ha yeh I have to add heaps of carbonates to my water to make it like yours!