Ah, I learn something new every day. I didn't know that the calcium carbonate that Greg Watson sold was dolomite. I should learn to read descriptions more. He does make an error
in the forumla for dolomite - it's CaMg(CO3)2, not CaMgCO3.
The general wisdom is that calcium should be dosed in a 3:1 to 4:1 ratio to magnesium.
With dolomite, this is not possible.
In dolomite, magnesium is bound to calcium in a 1.65:1 ratio based on molecular weight and EDTA chelation testing. So for every degree of GH that you raise the water with dolomite for calcium, you will raise it by 1.65 degrees for magnesium.
To raise GH by 1 dGH
with dolomite, you would add 31.06 milligrams
of water. (62% from magnesium, 38% from calcium.)
This dose will also raise the alkalinity by half a degree (.49840 dKH increase).
Using calcium chloride, magnesium sulfate, and sodium bicarbonate, it is possible to control ca, mg, and co3 levels individually.
----- Work / Calculations ----
Calcium = 40.078 g/mole
Magnesium = 24.305 g/mole
Carbonate (CO3) = 60.0089 g/mole
Dolomote (CaMg[CO3]2) = 184.4008 g/mole
1 dGH for calcium = 7.14691 ppm
1 dGH for magnesium = 4.33419 ppm
1 dKH for carbonate = 10.7145 ppm
Increase 1 dGH of magnesium & calcium in a locked 1.65:1 mg:ca ratio using dolomite (CaMg[CO3]2):
Calcium = 7.14691 ppm / (40.078 g/mole / 184.4008 g/mole) = 21.73418 mg/Liter
Magnesium = 4.33419 ppm / (24.305 g/mole / 184.4008 g/mole) = 13.18053 mg/Liter
Ratio = 21.73418 / 13.18053 = 1.64896 : 1 (Mg : Ca)
21.73418 mg adds 1 dGH for calcium & 1.64896 dGH for magnesium
21.73418 mg = 2.64896 dGH total
8.20479 mg = 1 dGH (.62249 dGH from Magnesium & .37751 dGH from Calcium)
Converted to Gallons:
8.20479 mg * 3.785412 liters/gallon = 31.05851 mg
10.7145 ppm CO3 = 1 dKH
10.7145 ppm / (120.0178 g/mole / 184.4008 g/mole) = 16.46224 mg/Liter
8.20479 mg / 16.46224 mg = 0.49840 dKH