how can I add both CO3 and HCO3 in phreeqc?

[maria]

Dear all,
I am quite beginner in phreeqc. My question could be a bit simple but I am quite confused.

I want to calculate the saturation indices of minerals. I have a dataset from a geothermal injection well and except major cations and anions, I have CO32- 5 mg/l and HCO3- 2338 mg/lt concentrations.
When I add the option of CO32- in the phreeqc interactive input file, I takes it as C(4). However, there isn’t any for HCO3. I tried to add it as alkalinity (although it isn’t) and specify it as HCO3. When I use both of these, the file is not running. When I remove alkalinity, the file runs well. I know that C(4) represents the total dissolved inorganic carbon. When I check the results, it takes the total C(4) (as CO32-) and divides into different carbon species, including HCO3. But HCO3 is actually way higher than CO3 so it doesn’t seem right to me.

I have pH data so I don’t want the calculation to adjust.

Is there a way to use both of them? I actually need to add them both because of the carbonate minerals and have carbonate equilibrium.

Thank you very much in advance. Your help would be tremendous.

Kind regards,
Maria

[dlparkhurst]

Really, the contribution of CO3-2 is negligible, but see https://phreeqcusers.org/index.php/topic,1644.msg5424.html#msg5424 for a discussion.

[maria]

Dear David,

Thank you very much for this. It is very clear to me, now.