from Chem_Geek's post:

You can take a bucket of pool water and add 6% bleach to it. 1/4 teaspoon of 6% bleach in 2 gallons is 10 ppm Free Chlorine (FC).
So...1/2 teaspoon in 1 gallon is four times the concentration Chem_Geek lays out.....

I prefer to use a glass eyedropper and add 10ml to 10 liters of water (that's 5 2-liter soda bottles). That's the same as figuring based on 10,000 gallons.....