Pool Calculators

[unclefudgly]

Hi all

I was just doing some figures from scratch for a new spa we're getting and my figures never agree with those from all the pool calculators around, the figures just do not match, the error seems to be in all cases regarding CH that none of the pool calculators take into account that calcium is only a percentage by weight of the total.

for example: CaCl2.2H2O - cal flake is 147g/mol but only 40g of that is actual Calcium, so all the calculations I get are out by a factor of 2.5 . Where am I going wrong? Or are all the pool calculators wrong?

Thanks

[chem geek]

I think your error is that you did not realize that Calcium Hardness (CH) is measured in ppm CALCIUM CARBONATE and not ppm calcium. Calcium carbonate has a molecular weight of 100.09 g/mole while calcium is 40.078 g/mole. Note that 100.09/40.078 = 2.50 which would account for your calculation error.

The Pool Calculator is the best to use for calculations. Not only does it have the most options for different chemical types, but it calculates an accurate calcite saturation index that is more accurate than most of the industry traditional LSI calculators (though the difference isn't large).

Just FYI. Total Alkalinity (TA) is also measured as ppm calcium carbonate (CaCO₃), but note that carbonate counts twice towards TA so if you are using sodium bicarbonate, you have to divide by 2 to get the TA. Chlorine (both free and combined) is measured as ppm chlorine gas (Cl₂). CYA is measured as Cyanuric Acid as you might expect. Borates are measured as ppm Boron ( B ) and not as boric acid or borate ion.

[unclefudgly]

I think your error is that you did not realize that Calcium Hardness (CH) is measured in ppm CALCIUM CARBONATE and not ppm calcium. Calcium carbonate has a molecular weight of 100.09 g/mole while calcium is 40.078 g/mole. note that 100.09/40.078 = 2.50 which would account for your calculation error.

The Pool Calculator is the best to use for calculations. Not only does it have the most options for different chemical types, but it calculates an accurate calcite saturation index that is more accurate than most of the industry traditional LSI calculators (though the difference isn't large).

Excellent! Thanks for clearing that up for me I was a bit lost.