Sandy Benoit is disgusted that vandals spray-painted obscenities on her pool deck. (CBC)

A Dartmouth family is struggling to understand why someone would spray-paint obscenities on the side of their pool deck.

Robert Benoit said he can't bear to look at the graffiti.

"I probably won't sleep at night," he told CBC News on Tuesday. "I'll just be concerned that they come back and probably do worse."

The pool was built last year as a haven for Benoit's 11-year-old daughter, Brianna, who has a rare genetic disorder that has left her blind and deaf.

Benoit said he wanted to give his daughter the palliative care she needs and spent his family's life savings on the salt-water pool and deck.

"She loves the water," he said. "But it's hard for my wife. My daughter is 11 years old now, and she's getting heavier. So, it's harder to take her around. So, we got the deck built so she'd have a better quality of life."

The deck was vandalized sometime early Tuesday. Benoit suspects it happened after the family went to sleep. Their neighbour next door called in the morning to alert them.

The vandalized deck faces a well-travelled path. Benoit's wife, Sandy, said other people with homes along the way have had problems, too.

"Our neighbours were getting a lot of teenagers and that throwing things in their yard, breaking windows and stuff," she said.

Police have taken photographs of the graffitied deck. However, the Benoits doubt the culprit will be found.

The couple worries vandals will come back if they remove the spray paint. They say the graffiti will have to stay up until they decide what to do.