Workers treated it with chemicals to kill the algae, but then the painted blue lining on the bottom began to peel."We've had some real problems with Vandalism at the beautiful Reflecting Pool," Mr Trump said in an earlier post on Friday, local time."Just like three days ago, they destroyed the grass outside of the Pool, they've also done everything possible to hurt the inside surface that was just installed."Agencies responsible for law enforcement and upkeep on the National Mall — the US Park Police, National Park Service and Interior Department — did not respond to AP's requests for comment.Mr Trump on Saturday followed up by posting that Park Police "have arrested multiple individuals for vandalizing our Nations magnificent Reflecting Poll", later correcting his spelling to "Pool"."Who would do such a thing? These are very serious crimes having to do with the destruction of National Monuments It was very rubbery."The Washington Post first reported on the arrest of Mr Hearn, who said he had a date to appear in court next month and was looking for legal help.The pool is marred by clouds of algae in the green water, with swaths of loose blue paint detaching from the bottom.Mr Trump insisted something nefarious had been going on at the scene."No different than the chemicals that were used on the National Mall, they used something similar in the Reflecting Pool to try to destroy and demean our beautiful work," he posted on Truth Social.That was an apparent reference to the discovery of large numbers "86" and "47" etched in discoloured grass on the National Mall the week before. Authorities investigating the matter said the numbers could have been meant as a threat to Mr Trump, the 47th president