The pool shock calculator works out calcium hypochlorite and liquid chlorine from free chlorine (fac), total chlorine (tac) and pool/spa volume. Enter what you have and the relationship is applied straight away, so you get the answer without working through the algebra yourself.
What Is the Pool Shock Calculator?
The pool shock calculator turns free chlorine (fac), total chlorine (tac) and pool/spa volume into calcium hypochlorite and liquid chlorine.
It is a quick way to get from the numbers you have to the number you need, without setting up a spreadsheet or reaching for a formula.
How the Pool Shock Works
Each result follows from the ones before it, and the calculator shows every step, so a surprising answer can be traced back to the input that caused it.
Round your inputs to the precision you actually know, and keep more precision than that in the intermediate steps.
Getting a Result You Can Trust
Run the calculation twice with slightly different inputs. A sensible calculator moves its output in proportion; a wild change points to a unit or a decimal point problem in what you entered.
Write the inputs down next to the answer. It takes a moment and it is the difference between a number you can explain and one you cannot.
A Worked Example
Working through an example, with free chlorine (fac) set to 10, total chlorine (tac) set to 5, pool/spa volume set to 2, the calculator returns calcium hypochlorite of -0.024, and liquid chlorine of -0.1284. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out calcium hypochlorite?
Enter free chlorine (fac), total chlorine (tac) and pool/spa volume. The calculator then works through the relationship and reports calcium hypochlorite and liquid chlorine.
What does the pool shock actually calculate?
It takes free chlorine (fac), total chlorine (tac) and pool/spa volume and converts them into calcium hypochlorite and liquid chlorine using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter free chlorine (fac)?
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Is the answer exact?
It is as exact as the formula and the inputs allow. The method itself is the standard one for this problem, so the only sources of error are the figures you enter and the precision you ask for.
Do I have to fill in every field?
Only the fields a particular result depends on. If you leave one blank, the results that need it simply show a note instead of a number, and everything else still works.