will have uncontrolled growth of "primary production": photosynthetic critters, i.e., algae. Once nutrients are depleted, algae will die, rot, and stink, then return somewhat when decomposition releases the bound nutrients (mostly nitrogen and phosphorus) into solution. Some nitrogen will gas out.
The reflecting pool was filled with a rich soup. Some algal cells made it past whatever filters they used, and could also be introduced by birds. What is missing from this soup is the next step in the food web: grazers, the animals which consume the trapped energy and molecules in the algae.
The pool is like a meadow with no cows or sheep to graze it, growing long, long grasses.
The scientist in the post is correct in saying that the pool needs grazing; he suggests Daphnia. These are tiny free-swimming crustaceans, familiar to aquarium keepers as fish food. Daphnia, a filter feeder, consumes free-floating unicellular algae; I don't think it would do much to the mats and strands in DC.
Other grazers I have suggested in earlier posts: chironomid midge larvae, snails, fish. There's a wide choice of critters that graze on filamentous algae. Eventually, duck feet will carry some in.
This is an ecosystem with a food web, not a swimming pool.
Maybe Freedom 250 could sponsor an algae-grazers rodeo. Yeehaw! Git along li'l Daphne!
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