Ann Fuller of the Children's Hospital of Eastern Ontario said the children, aged six to 17, were checked for mild symptoms of respiratory distress, coughing and vomiting after swimming at the Calypso Water Park in the afternoon.
She said in an interview Tuesday evening that the children's symptoms were "mild across the board" and that the 13th child was expected to be sent home soon as well.
Ginette Robert, an executive with Valcartier Vacation Village, the owner of the Calypso park, said the children were sent to hospital as a precautionary measure once they started "feeling sick" after swimming in the park's wave pool.
She said that Ministry of Health inspectors have since tested the pool and found there were no leaks of chlorine or other chemicals in the water.
"Everything was balanced (and) everything was normal as it should be," Robert said in a phone interview from Quebec City.
She said that more than 500 people were in the pool during the afternoon, but that only the 13 children experienced symptoms of illness similar to exposure to a chlorine leak.
The Ministry of Health was not immediately available for comment.
Twelve people were transported to hospital after a chlorine leak at a St. Catharines, Ont., community pool on July 12.
That leak also saw toxic gas waft out from a utility building next to the pool, while nearby residents were advised to lock their windows and doors to block the fumes.