You'll find that the higher the chlorine level, the more you'll lose in a day. You may have gone from 19 ppm to 8.5, but tomorrow you may go from 8.5 to 5....my point being that you probably won't have to spend the $2.50 a day when you're running normal chlorine levels. For example, my pool is in Northwestern Louisiana, in full sun from about 8 AM til about 7PM during the summer. Today's air temp topped out at 104, and the heat index with 87% humidity was 109. I started with 8 ppm chlorine this morning, and just tested it a few minutes ago at 4 ppm (CYA 80). A little low, so I added the large size jug of bleach, which in my pool is a 4 ppm increase. Not bad, if you consider that it's been two days since I had to add any--the last time I added was Saturday--put one jug in in the morning because I had a pool full of kids coming over for the day, and then added another jug that evening after they all got out. None since then til tonight.

With my CYA at 80-90 (intentionally), I go through about 4 of the large jugs weekly during the summer. During the winter, after the water temp drops below 60 or so, I only use 1 of the larger jugs every week or so, and I keep my pool open all year--it never closes.