[help] Balls for a ball pit?

Has everyone ever bought balls for a ball pit to let your dog play around in? I have an inflatable kiddie pool that I usually put water in for them to splash around in, but thought balls would also be fun. I figured it could also be a fun way to play hide/seek with treats. But, I am not sure if this is a terrible idea in terms of safety...any thoughts?Any recommendations in balls would be welcomed as well. via /r/dogs http://ift.tt/2rAVNIt