Destroying kH via acids... again!

[Soggy]

For purposes of discussion... and my peace of mind,

When HCl or pH down(H2SO4) is added to water with high kH.

what happens to the bicarbonates & carbonates in this buffer equation

H2CO3 H+ + HCO3- H+ + CO3--

I know the strong acids above will dissociate and "eat up" some kH.

But what i do not know is what happens to the carbonates and their Ca++/Mg++ pair

Does the acid break up the bicarbonate to release CO2 and form calcium chloride/sulphate salt?

 

[jonny_ftm]

There's an error in your equation

H+ + HCO3- H2O + CO2
or
2HCl + CaCO3 H2O + CO2 + CaCl2

The gas you see when dropping HCl on calcareous rocks is CO2. Same happens with H2SO4 acid, with formation of CaSO4 salts

In water, Kh will be rather in the form of Ca(HCO3-)2

Ca(HCO3-)2 + 2HCl 2H2O + 2CO2 + CaCl2

In all cases, these KH- / PH- products will add drastic amounts of Cl or SO4 salts, equally to the Calcium/Magnesium salts they precipitate, thus leading to long term problems. The best is to have a balanced source water from the beginning

 

[Soggy]

wow. thanks for clearing that up jonny!

So, while strong acids, reduce kH, it does nothing to gH. since the precipitated salts are water soluble themselves.

Is the effect of tannins and other organic acids similar?

 

[jonny_ftm]

Hi,

Yes, but tanins... are much weaker acids than HCl, so the drop in KH is minimal.

The problem with these products will be the addition of Cl or SO4 for every Ca and Mg carbonate salt. I'm not sure on the long term safety of these products. Maybe Tom can help us or some one that tested them. The most natural and recommended way is still to drop KH with using osmose water