President Donald Trump's remodeled Lincoln Memorial Reflecting Pool has turned chartreuse from an algal bloom. Park service workers are struggling to address the issue days after its more than $14 million renovation. The pool, completed and refilled earlier this month, was meant to be an azure expanse. However, it faces harsh challenges from chemistry and biology. The pool is larger than 10 Olympic-sized pools and uses water from the often-fetid Tidal Basin. Algae has plagued the site for over 100 years. Workers are using chemicals and ozone nanobubbles to combat the algae. Experts suggest draining and refilling the pool with fresh water.