I believe it is the air in the hollow hoop that keeps them afloat. I don't know if you have to seal them where they connect though. Someone here uses them (maybe goodkarma), so hopefully they will chime in.

Anne

I have seen hula hoops used to contain floaters. They float. I've also seen styrofoam used like that which you use to insulate pipes with.

So is it only floaters that people use in the hoops? I guess I'm confusing the hoops with something like the smaller round styrofoam things that have a pot in the middle of them.

I have used a hulahoop to corral fish food and hyacinths. It works very well if you put a leash on it to hold it in place. I had to tape two together to prevent the food from washing out.

Thanks Everyone!

I snagged some soft frisbee's out of the target dollar bins and am finding them pretty handy for floating islands.

~dianne

I use grey pipe insulation to contain my plants. You can just ties the ends together or, if you want a place for baby fish to hide, use a black laundry basket (I get mine a Dollar Store). Tape a couple of pieces of pipe insulation around the handles with electrical tape. The laundry basket provides a good place for baby fish to hide and it keeps tender plant roots safe from hungry fishies!

If you are looking for a small inexpensive hula hoop they are available for $1 at the Dollar tree. They have ribbon wrapped around clear plastic tubing and the thing that holds the hoop together is easy to remove and silicon for water tight seal. I am making mini water lily protectors with these hoops and big hole netting.