Decarbonation by Boiling

[FourSeasonAngler]

Does anyone do this?

I have a VERY high bicarbonate level in my tap water: Bicarbonate, HCO3: 335 ppm, but relatively low calcium levels (61 ppm). Reading the Bru n' Water knowledge page I see that is is possible to bring my bicarbonate levels down to +/- 185 ppm by boiling and stirring vigorously to precipitate the bicarb & calcium.

I just don't see this happening in the water that I boil at home though, say for example when I make spaghetti or hard boiled eggs. If I fire up 20 gallons of tap water on my brew rig, get it to a rolling boil, and steam myself while stirring vigorously and DON'T see the precipitate I'll be really pissed.

 

[pjj2ba]

I thought about it, but decided it was too wasteful of propane. I finally settled on using pickling lime (Calcium hydroxide) to precipitate out the carbonates. I mix it up and let it set overnight and then pump it off of the precipitate. I think you can add some extra Ca (chloride or sulfate - I like Cl) to help drop out even more carbonates, and also keep your final Ca levels up where they should be

 

[mabrungard]

Remember that you may not initially see any precipitate when boiling. The calcium carbonate is microscopic and it takes some time for the water to quiescently settle out the precipitant.

As the tuba man points out, pre-boiling can be a bit of an energy hog. Lime softening may be a cheaper alternative. However, it does require a bit more skill, ability, and patience to execute.

 

[pjj2ba]

........However, it does require a bit more skill, ability, and patience to execute.

I should have mentioned that after the water is in the mash tun (or hot liquor tank) I adjust the pH back down with phosphoric acid. You really need a pH meter for this.

 

[FourSeasonAngler]

I should have mentioned that after the water is in the mash tun (or hot liquor tank) I adjust the pH back down with phosphoric acid. You really need a pH meter for this.

That is my only qualm with the pickling lime treatment. I don't have a pH meter and buying one is not in my budget.

My boil kettle is rigged up to a natural gas burner, so the cost of boiling 20+ gallons of water is not a concern.

I guess the only way to really know how this will go is to give it a shot and see for myself.

 

[FourSeasonAngler]

Remember that you may not initially see any precipitate when boiling. The calcium carbonate is microscopic and it takes some time for the water to quiescently settle out the precipitant.

As the tuba man points out, pre-boiling can be a bit of an energy hog. Lime softening may be a cheaper alternative. However, it does require a bit more skill, ability, and patience to execute.

My online research yesterday did not turn up any solid conclusion either way concerning whether to let the water cool overnight and decant off the cooled water over the precipitate, or to only wait until precipitate is apparent before decanting.

Also, would the addition of an air stone in the boil kettle during boiling help to drive off Co2 and further precipitate carbonates? I have stainless steel lines and stainless steel air stones available. It just seems like splashing around 20 gallons of boiling water would be a burn hazard.

I will definitely give the powdered chalk additions during boiling a shot though. I do understand how nucleation works and this should help speed up the precipitation.

 

[mabrungard]

By the way, the relatively low calcium content can limit the degree to which you can decarbonate water. You can calculate the potential level of decarbonation by playing with the equation included on the Water Knowledge page of the Bru'n Water website. The lower limit for calcium in boiled water is somewhere in the 12 to 20 ppm range. Using that range of values, you can back-calculate what the resulting bicarbonate concentration might be.

I'm assuming that there is a decent amount of sodium in that water since the bicarb is so high and the calcium is not.

 

[FourSeasonAngler]

By the way, the relatively low calcium content can limit the degree to which you can decarbonate water. You can calculate the potential level of decarbonation by playing with the equation included on the Water Knowledge page of the Bru'n Water website. The lower limit for calcium in boiled water is somewhere in the 12 to 20 ppm range. Using that range of values, you can back-calculate what the resulting bicarbonate concentration might be.

I'm assuming that there is a decent amount of sodium in that water since the bicarb is so high and the calcium is not.

Yes, I did calculate that I should be able to bring my bicarb level down to around 185 from 335 using the practical limit of 12 for my Ca level. Here is the summary of the Ward labs water report for my tap water:

Sodium, Na: 35
Potassium, K: 16
Calcium, Ca: 61
Magnesium, Mg: 22
Total Hardness, CaCO3: 244
Nitrate, NO3-N: 0.1 (SAFE)
Sulfate, SO4-S: 13
Chloride, Cl: 12
Carbonate, CO3: < 1
Bicarbonate, HCO3: 335
Total Alkalinity, CaCO3: 275


Sodium does not seem to be that high, but my bicarb level is definitely high.

My plan is to give the boiling a shot and tinker with a bit of gypsum to bring the Ca levels back up, then use a bit of acid malt if necessary or possibly some lactic acid depending on what my numbers look like after going through the speadsheet using my next planned grist.