I understand how FC and pH change over time based on sun, usage, etc... but, assuming normal evaporation and refilling and no draining of water, how are CH and CYA affected by evaporation? Are they both not affected by evaporation and essentially stay the same over the course of a summer, unless a large amount of water is pumped out? Or do they slowly decrease over time with standard evaporation and refill with water that essentially has zero CYA and CH?