Wessex Water - report as of November 07

Joined
10 Jun 2007
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963
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Dorset, UK
pH- 7.3
Ammonium - 0.01 mg NH4/l
Nitrite - 0.01 mg NO2/l
Nitrate – 39 mg NO3/l <-------------------------- Im dubious as to this one
Hardness - 265 mg CaCO3/l
Free Chlorine – 0.25 mg Cl/l
Total Chlorine – 0.28 mg Cl/l
Magnesium – 1.9 mg Mg/l

Fresh from the horses mouth, as it were
 

JamesC

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3 Jul 2007
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Location
Bexley, Kent
1.9mg/l Mg = 7.8 mg/l MgCO3 as CaCO3

Hardness - MgCO3 gives CaCO3
265 - 7.8 = 257.2 mg/l CaCO3 = 103 mg/l Ca

If you follow that you have a Ca : Mg ratio of 54 to 1, or in other words not much Mg.

James
 
Joined
10 Jun 2007
Messages
963
Location
Dorset, UK
JamesC said:
1.9mg/l Mg = 7.8 mg/l MgCO3

Hardness - MgCO3 gives CaCO3
265 - 7.8 = 257.2 mg/l CaCO3 = 103 mg/l Ca

If you follow that you have a Ca : Mg ratio of 54 to 1, or in other words not much Mg.

James
that was my assumption as well.. i shall carry on dosing it
 

JamesC

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Bexley, Kent
Yes atomic weights are used.

This is how I arrived at the answer:
Atomic weights: Mg=24.3, C=12 and O=16
So MgCO3 we have 24.3 + 12 + (16x3) = 84.3

To get mass MgCO3 from Mg:
1.9 x (84.3/24.3) = 6.6g

But as we are talking in equivalents of CaCO3 and not MgCO3 we have to convert.
So (18/15)x6.6 = 7.9g

Not quite the 7.8g as above but I just use the quick calculation of multiplying by 4.1
1.9 x 4.1 = 7.8

James
 
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