Potter Pool reopened Tuesday after vandalism Friday prompted the city to close it for cleaning.
Sometime Friday night, vandals got through a door mistakenly left unlocked, according to a police report released Tuesday.
The suspects took a fire extinguisher from the office wall and sprayed it into the pool, the report said.
The damage was discovered Saturday by employees.
City Manager Joe Thomas said the pool had to be closed for three days while employees cleaned it to remove the chemicals from the pool.
The pool was recertified and given the go ahead to reopen Tuesday morning, he said.
Thomas said there was no long-term damage.
Police noted in the report there was no suspect information.