The idea is to dilute the LC in a water solution to mimic the pool. So adding 1 gallon of LC to 10,000 gallons in a pool is 1: 10,000.
I mis-wrote above..my eyedropper (glass) is 1 ml, not 10. So....1 ml of LC in 10 liters of water (five soda bottles full) is the same as 1 gallon in 10,000 gallons.

I mix it up in a 5 gallon bucket, then test it with my trusty FAS-DPD test. Whatever it reads is the concentration of the LC/bleach.

However, it's a good idea to test the water FIRST before you add the LC because public water frequently has an FC reading, and you'll want to subtract that.