Water tested by Lab

[Myvortex]

Hi Randy, Boomer
I was hoping you could help interpret these results. Specifically, when I test calcium using Lamotte Calcium test for fresh or salt (model cadr), I get a reading of 517ppm Ca.
I had my water tested by a water chemistry lab 2 times and they continue to report the water has having half (250ppm) this amount of calcium. Also, looking at the hardness (CaCO3) of 6555ppm should equal 2622 ppm Ca++. (0.4 x 6555). What am I doing wrong? Is this data impossible given the hardness and the calcium levels? Any observations would be appreciated.
TDS calculation (mg/L) ** 34836
Hardness (mg eq/L CaCO3) 6555
SiO2 calculation (mg/L) 0.94
pH 8.1
Conductivity (uS/cm) 56200
Alkalinity as HCO3- (mg/L) 210
Bromide (mg/L) 88
Sodium (mg/L) 10500
Potassium (mg/L) 460
Magnesium (mg/L) 1440
Calcium (Ca) (mg/L) 250
Chloride (mg/L) 19200
Fluoride (mg/L) 1.5
Nitrite(mg/L) NONE DETECTED
Nitrate (mg/L) NONE DETECTED
Phosphate (mg/L) NONE DETECTED
Sulfate (SO42-) (mg/L) 2800
Total cations (meq/L) 599
Total anions (meq/L) 604
SiO2 calculation (mg/L) 1.0

TDS calculation (mg/L) ** 34836
Hardness (mg eq/L CaCO3) 6555

 

[sowellj]

hmm .. the fact that there is a factor of 2 difference sounds like a testing error somewhere. Do you get ~500 Ca if using a differnt brand test kit. If so, I would be inclined to say that someone in the lab is only using half the volume of sample they are supposed to.

 

[Randy Holmes-Farley]

The hardness includes magnesium and calcium (probably strontium too), even though it is in units of CaCO3 equivalents. So it is not a very useful measure in seawater.

I do not know what happened with the calcium measure.

What lab?