[lula]

I have read they can’t add certain chemicals because it drains into waterways and will harm fish, aquatic life and water birds.

[Texas Eagle]

The water doesn’t circulate????

[desertsolitaire]

I have heard that too. Local wildlife may drink directly from it also

[Skwor]

Plenty of chemicals they can add, they will and they well sweep / vacuum up the dead microbes. In the end it will be blue again unless they decide not to clean it.

[libertylover]

I have read they can’t add certain chemicals

As a former pool owner, I can tell you that it doesn't take long to go yucky green without chemicals.