Thanks for the info. I think I can visualize the system functionally, now.

Quote Originally Posted by martinkennedy View Post
With the water falls and mist and evaporation that goes along with it, the need for replacement water increases. Replacing the water at a higher rate in effect acts as a counter balance to higher CYA.
Actually, that's not correct. Losing water to evaporation has no effect on the total quantity (mass) of CYA present in the pool water, just as solar evaporation does not lower the ocean's salinity. The reason is that the water vapor -- evaporated water -- is essentially distilled water, free of all chemicals. Some volatiles may be present, but CYA does not have a significant volatile fraction.

There are 3 known ways to lower CYA:
1. Drain (as liquid water, not evaporate as water vapor) and replace.
2. Precipitate with melamine, making a huge mess.
3. Biodegrade with heterogeneous 'slime' composed of algae and soil bacteria. This happens naturally, but is unpredictable as to rate of degradation (2 weeks to months) and endpoint (nitrogen gas, nitrates, or ammonia).