My in ground pool on Hatteras Island was covered with five feet of salt water during hurricane Irene. I just finally got down to inspect the house and pool and have found what looks like barnacles growing on sides and bottom of the pool. It's been a month since the pool had been running. Is there a special chemical I should add to the pool to kill these things. I'm closing the pool and would like to kill them so I don't have a problem in the spring

If they're actually barnacles, chlorine will kill them. Kind of a unique problem!

That being said, calcium scale often looks like tiny barnacles. Any chance of a picture?

In another life I was a navy diver and busted many barnacles off of ships. If you can get in the water with goggles and take a look at the suspects that will help. Barnacles are live creatures, you will see them extending filaments trying to catch and eat plantain. I don't think they could grow/survive in your pool. They need a living ecosystem to support life.

What ever is growing on your pool sounds like it might have to be removed with some elbow grease. Maybe a pumice stone.