formula for bicarbonate removal by boiling

MattHollingsworth · 06-28-2009, 06:26 PM

The only formula I found is from Dave Miller's Homebrewing Guide from the 1990s. He says that when you boil to remove bicarbonate that you remove 3 ppm of calcium for every 5 ppm of carbonate that you remove.

My water has 386 ppm bicarbonate and 86 ppm calcium.

So, basically, I should be able to remove 143 ppm of carbonate leaving me with 243, if I boil.

I remember reading about adding calcium before the boil to allow more bicarbonate to precipitate out. Anybody have info on that, or on formulas?

Thanks.

MattHollingsworth · 06-28-2009, 06:31 PM

And, does magnesium also precipitate while the calcium is doing the same?

Poindexter · 06-29-2009, 01:35 AM

The Mg will depend on the ionic state, but mostly yes.

The aqueous equilibrium state is calcium bicarbonate, Ca(HCO3)sub two.

When heated, CO2 comes out of the solution (you knew already the solubilty of CO2 varies with temperature.)

As the CO2 leaves, the equilibrium shifts towards H2O and CaCO3, the latter, calcium carbonate as distinct from Calcium bi carbonate. Heated with the CO2 blown out the Calcium carbonate shows up on the floor of your tea kettle as that white stuff, boiler scale.

Just bring whatever water you got to a boil, pour off most of the water before it re-absorbs CO2 and get your pot clean before the white stuff sticks. Then brew with whatever water you got to find out what it is good for. In most places trying to add chemicals to get rid of others turns into a vicous cycle.

If you end up that pre boiled tap water water alone isn't good enough, you might try preboiled tap water mixed 50-50 with off the shelf distilled water. Your carbonate numbers aren't that bad really, I have seen much worse.

Poindexter · 06-29-2009, 01:42 AM

I drew the equilbrium equation out long hand in here if you like. Relevant chemistry starts at 2:02.

[youtube]42x0mP-q_04[/youtube]

MattHollingsworth · 06-29-2009, 07:36 AM

Quote:

Originally Posted by Poindexter

The Mg will depend on the ionic state, but mostly yes.

The aqueous equilibrium state is calcium bicarbonate, Ca(HCO3)sub two.

When heated, CO2 comes out of the solution (you knew already the solubilty of CO2 varies with temperature.)

As the CO2 leaves, the equilibrium shifts towards H2O and CaCO3, the latter, calcium carbonate as distinct from Calcium bi carbonate. Heated with the CO2 blown out the Calcium carbonate shows up on the floor of your tea kettle as that white stuff, boiler scale.

Just bring whatever water you got to a boil, pour off most of the water before it re-absorbs CO2 and get your pot clean before the white stuff sticks. Then brew with whatever water you got to find out what it is good for. In most places trying to add chemicals to get rid of others turns into a vicous cycle.

If you end up that pre boiled tap water water alone isn't good enough, you might try preboiled tap water mixed 50-50 with off the shelf distilled water. Your carbonate numbers aren't that bad really, I have seen much worse.

Thanks!

I'm using Palmer's water spreadsheet. Basically, I'm going to assume that I can remove 143 ppm of bicarbonate, leaving me with 0 calcium and 243 bicarbonate. I then adjust with distilled water and salts to get to the RA that I want. When I finished the sheet, I put the calcium and bicarbonate numbers back to 86 and 386 respectively and have my sheet adjusted so that it's a nice RA with or without the treatment, but so that it's ideal with the boiling but still within the average ranges for high and low RA even if the numbers stay as they were.

No chemicals for me. Don't wanna deal with it. Just salts and distilled water.

Thanks for the info.