Algaes very good at removing CO2 from the atmosphere. A pool of that size, with the algae bloom of that size, will actually be doing a small amount of good. More than several trees actually. So yay for an accidental win for the environment
I agree about the massive filter/continual water replacement. But actually part of the problem is the wanting to keep a very large body of water in essentially a sterile/dead condition. Any large or small body of water (even a puddle in the desert an hour after rain) is teeming with life. Left to nature it reaches a state of balance (larger creatures eat the phytoplankton/algae and keep it in check, other creatures eat them). But because the ideal aesthetic is apparently "death" they are locked into a constant battle with life that they are always going to lose. It reminds me a bit of the desire to create a "perfect" monoculture lawn in places like Utah. Technically more achievable but so much effort and why?
Obviously Trump is a particularly egregious example of the impulse to force his own desires upon reality. But the Reflecting Pool feels like a much wider example of hubris than just him.