I wonder what kind you have. I have tried the bubble types and to be honest they scare the hell out of me. You probably saw Lethal Weapon where the guy fell in the pool with a plastic cover on it and was helpless. That wasn't fake, it's a fact.
The only covers I would want is the kind that roll out and you can walk on them.
My son being the smart a** that he could be sometimes; decided to jump into the pool with the blanket on top. It was in the shallow end, (about 3'). He jumped in feet first, to prove that he could get out. His arms were at his side and once in, he couldn't move. We had to drag his surprised little butt out of the pool to get him loose. He's married with children now, so this was a while ago. That's why those things scare me.