Shelly Ann,

It looks to me like you may be a candidate for a higher CYA pool, like CarlD suggested, because if I'm reading this thread correctly, you're still losing a good bit of Cl during the day but not during the night....

My pool is in full sun 12 hours a day also, so I run my CYA up to the 80-90 mark and run higher chlorine levels. Pool stays clear, and I only add bleach about twice a week. Even though the best guess chart recommends 5 minimum and 10 max, I tend to keep my Cl around the upper end of that--usually 8 or 9 ppm. By doing that, it takes 3-4 days before I drop down to 5 and need to up it again. Most people will tell you that it's too high, but in a pool that gets full sun all day every day, it's working well for me. If I were you, and if the chlorine loss is during the day but not at night, I would try bumping it up to around 50 and see what that does to your chlorine consumption. If it slows down, then bump it up about 10 ppm at a time until you get to a point that works for you.

Janet