Water Question - Which calcium to use in water calculator?

[dkeller12]

Hey everyone - I recently got my local water report and noticed that it contains two calcium measurements and I am not exactly sure which one to use. Can someone let me know which I should use and why?

Thanks,

 

[mabrungard]

I’ve got the feeling that the lower one is reporting as ‘CaCO3’. The top one is what to use in most water calculations. There is a converter in Bru’n Water that could help confirm that the lower result is as CaCO3.

 

[dkeller12]

Thank you for the response Martin. I have been using your Bru'n Water spreadsheet for my water profile, so I appreciate the assistance.

I took the top reading (39 ppm) and used the calculator at the bottom of the Water Report Input tab to come up with 15.6 ppm, which is close to the 13 ppm that shows in the bottom of the report, so knowing that, I should use the 39 ppm, correct?

If using 39ppm is the right one to use, when I entered it into the spreadsheet it is giving me the Water Report unbalanced message. Any ideas as to know that would happen (see below)? I must be missing/doing something wrong.

Again, I really appreciate your expertise.

Don

 

[mabrungard]

The alkalinity is reported as 'bicarbonate', so don't run that value through the conversion. Leave bicarb at 25.

That is one confusing water report. The other concern is: which units is magnesium being reported in? It too can be reported as 'CaCO3'.

 

[dkeller12]

I changed the bicarb to 25 and I am still getting that error. The magnesium is ppm per the report. I attached the entire report below which includes what measure they are in. Ignore the second column of data as that is another plant which is not where my water comes from. Screenshot of updated bicarb figure in calculator is below water report.

Can you think of what it off here?

 

[Silver_Is_Money]

The relationship is:

Total Hardness (as CaCO3) = 2.5(Ca) +4.12(Mg)
(rounded)

Therefore this relationship clearly shows us that your total hardness (as CaCO3) is 39 and your calcium is 13.

Also, it appears as if the alkalinity is being reported as HCO3- (bicarbonate), so your bicarbonate is 25. And that would make alkalinity as CaCO3 out to be 20.5.

 

[dkeller12]

The relationship is:

Total Hardness (as CaCO3) = 2.5(Ca) +4.12(Mg)
(rounded)

Therefore this relationship clearly shows us that your total hardness (as CaCO3) is 39 and your calcium is 13.

Also, it appears as if the alkalinity is being reported as HCO3- (bicarbonate), so your bicarbonate is 25. And that would make alkalinity as CaCO3 out to be 20.5.

That makes sense, and being new to water chemistry, is something I didn't know. When I enter 13 as my calcium, the error goes away and now I know why and the relationship between Ca and Mg.

Thank you both for getting this squared away and help me out. I just started to get into water and wouldn't have made it far without your help.

Cheers!!!