New China Shop Topic: How Accurate is the Pool Calculator?

[CarlD]

Richard, that's the first good defense I've read of the deviation in the Pool Calculator from the formula. THAT is an explanation I can accept. It also points out there is a potential inaccuracy in the FC section. Naturally, neither the PC nor the formula take into account any degradation or breakdown in the chlorine over time. I'm confident your coefficients are correct but where do they come from. BTW, how many grams/mole are there in CL2 and NaOCl?

Madwil, I suppose it's a difference of definition but the VARIABLE "Concentration" must be defined as 4 digits to the right of the decimal point because available VALUES can use any of the 4 places...LC would be expressed as .125, while regular bleach is .0525. Each uses only 3 digits, but 4 are still needed.

Carl

[madwil]

That's why it's a place holder...
0's at the end of a number, without decimal places, are not significant.
0's after the decimal, before numbers, are not significant if 0 precedes the decimal.
Otherwise, you could call 2 ppm .000002 and say it's 6 sig dig, when it is only 1!
Consider scientific notation- a.bc x 10 to n power- a.bc is sig, not the location of the decimal point, with regards to accuracy/precision of measurement
When you mult/div numbers, the lowest number of sig dig in any of the factors is the number of sig dig in the product
When you add/sub, the number with the highest multiple of 10 becomes you last sig dig (1,250 + 2, is still 1250 for significance...)

[chem geek]

BTW, how many grams/mole are there in CL2 and NaOCl?

CL2 is 70.9064 g/mole while NaOCl is 74.44 g/mole. That's where those numbers came from in the formula in my post.