Algae blooms, peeling paint, and a host of fixes from hydrogen peroxide to nanobubblers have made it hard to diagnose what’s wrong with the Reflecting Pool—let alone how to clean up the mess.

President Donald Trump’s more than $14 million Lincoln Memorial Reflecting Pool renovation was completed just over a week ago, with its more than 300,000 square feet refilled with 6.5 million gallons of clean water.

The Interior Department said the algae is residual after supply lines sat dormant for weeks.

There’s a new twist in the ongoing saga to clean up the Reflecting Pool. Some of the new “American Flag Blue” paint used to coat the bottom appears to be peeling away.

U.S. President Donald Trump believed he had a solution to the reflecting pool's algae problems: painting its bottom a particular shade of blue. Less than two weeks after the repair work finished, the algae is back.

The "American flag blue" finish has turned into something else entirely, but why has algae reappeared?