Chlorine levels don't stay consistent; it is normal for the level to drop during the day especially when there are swimmers. If your CYA level is low, it also makes it more difficult to keep chlorine in the pool.

Why are you needing to refill so often? Are you backwashing after every time you vacuum or are you vacuuming to waste?

Why so much dirt? Lots of kids going in and out of the pool? It is impossible to keep an outdoor pool pristine --- trust me. I try!