01-29-2006, 08:33 PM
Join Date: Mar 2004
Location: Leverett, Mass
iTrader Positive Rating: 100%
Time to bring this back to life as I need to calibrate my test kits....
From the krib, http://www.thekrib.com/Plants/CO2/ha...arryfrank.html
By definition, 1dGH = 10 mg/liter CaO By definition ppm Ca is not for elemental calcium but for ppm CaCO3.
Atomic Weight Ca = 40, O = 16, CaO = 56
So 10 mg/liter CaO contains 40/56 *10 = 7.143 mg/liter of Ca
Atomic weight CaCO3 = 100
So 7.143 mg/liter of elemental Ca would be expressed as 100/40 * 7.143 = 17.8575 mg/liter(ppm)CaCO3.
1dGH = 17.86 ppm CaCO3 and 7.143 ppm Ca2+.
I want to make a GH test sample using 1 gallon of DI water. According to the Fertilator, adding .5grams CaCl2+2H2O yields 36.1mg/l Ca. Divide 36.1/7.143=5.05 degree GH. Is this correct?
Using baking soda, NaHCO3, to adjust kH:
Info below from the same source as above:
1dKH = 21.8 ppm HCO3 |
How to use these conversion factors:
If you have alkalinity in ppm or hardness in ppm divide by 17.86 to get degrees.
If you want to raise the alkalinity by 1dKH using CaCO3: use 17.86 mg CaCO3
If you want to raise the alkalinity by 1dKH using NaHCO3:
mw Na = 23 using molarity:
mw HCO3= 61
mw NaHCO3= 84
1dKH= 21.8 ppm HCO3
21.8 *84/61=30 mg/liter of NaHCO3
0.358 mMoles * 84(mwNaHCO3) = 30 mg/liter of NaHCO3
Unfortunately I do not know how to interperate that
. I would like to add NaHCO3 to 1 gallon of DI to make my test solution. If necessary I can make the gallon with a high kH then dilute that sample as necessary for easy measurment. I have graduated cylinders and syringes so dealing with measurment accurately is easy enough. I also have a gram scale with a 0.1 readout.
Would it be possible to use the same gallon of DI for both tests? The CaCl2+2H2O should not affect the kH but would the NaHCO3 have an effect on the GH reading?
Last edited by dennis; 01-29-2006 at 08:36 PM..