In this situation, the dissociation constants for the much faster reactions

H₂CO₃ ⇌ H⁺ + HCO⁻
₃ ⇌ 2 H⁺ + CO²⁻
₃

allow the prediction of concentrations of each dissolved inorganic carbon species in solution, from the added concentration of HCO⁻
₃ (which constitutes more than 90% of Bjerrum plot species from pH 7 to pH 8 at 25 °C in fresh water).^[54] Addition of HCOHCO⁻
₃ ⇌ 2 H⁺ + COHCO⁻
₃ (which constitutes more than 90% of Bjerrum plot species from pH 7 to pH 8 at 25 °C in fresh water).^[54] Addition of HCO⁻
₃ will increase CO²⁻
₃ concentration at any pH. Rearranging the equations given above, we can see that [Ca²⁺] = K_sp/[CO²⁻
₃], and [CO²⁻
₃] = K_a2 [HCO⁻
₃]/[H⁺]. Therefore, when HCO⁻
₃ concentration is known, the maximum concentration of Ca²⁺ ions before scaling through CaCO₃ precipitation can be predicted from the formula:

_max increases from freshwater to saltwater, and decreases with rising temperature, pH, or added bicarbonate level, as illustrated in the accompanying graphs.

The trends are illustrative for pool management, but whether scaling occurs also depends on other factors including interactions with Mg²⁺, B(OH)⁻
₄ and other ions in the pool, as well as supersaturation effects.^[55][56] Scaling is commonly observed in electrolytic chlorine generators, where there is a high pH near the cathode surface and scale deposition further increases temperature. This is one reason that some pool operators prefer borate over bicarbonate as the primary pH buffer, and avoid the use of pool chemicals containing calcium.^[57]

Solubility in a strong or weak acid solution

Solutions of strong (HCl), moderately strong (sulfamic) or weak (acetic, citric, sorbic, lactic, phosphoric) acids are commercially available. They are commonly used as descaling agents to remove limescale deposits. The maximum amount of CaCO₃ that can be "dissolved" by one liter of an acid solution can be calculated using the above equilibrium equations.

• In the case of a strong monoacid with decreasing acid concentration [A] = [A⁻], we obtain (with CaCO₃ molar mass = 100 g/mol):

[A] (mol/L)	1	10−1	10−2	10−3	10−4	10−5	10−6	10−7	10−10
I The trends are illustrative for pool management, but whether scaling occurs also depends on other factors including interactions with Mg2+, B(OH)− 4 and other ions in the pool, as well as supersaturation effects.[55][56] Scaling is commonly observed in electrolytic chlorine generators, where there is a high pH near the cathode surface and scale deposition further increases temperature. This is one reason that some pool operators prefer borate over bicarbonate as the primary pH buffer, and avoid the use of pool chemicals containing calcium.[57] Solutions of strong (HCl), moderately strong (sulfamic) or weak (acetic, citric, sorbic, lactic, phosphoric) acids are commercially available. They are commonly used as descaling agents to remove limescale deposits. The maximum amount of CaCO3 that can be "dissolved" by one liter of an acid solution can be calculated using the above equilibrium equations. In the case of a strong monoacid with decreasing acid concentration [A] = [A−], we obtain (with CaCO3 molar mass = 100 g/mol): < [A] (mol/L) 1 10−1 10−2 10−3 10−4 10−5