What was your chlorine loss overnight?

For reference, in your pool, each gallon (4 quarts) of 6% bleach will add about 3.2ppm of chlorine. Use that to help you determine doses of bleach to add. With a CYA of 80, you need to keep your chlorine between 5-10ppm ALL the time unless you are fighting something in the water. Then, your shock level will be 20ppm and in a pool with metals in the water, you really want to avoid shocking the pool if you can.