Bear,
I'm not sure that the CYA-Chlorine bind-time is all that critical here. Even assuming the best case, that the chlorine is protected immediately by the CYA, some part of the chlorine is still subject to destruction by the UV rays (that typical daytime chlorine losss that we all experience). My WAG is that up to 1 ppm of chlorine will be unecessarily destroyed by that 2-3 hours of sunbathing.