There is a TON of information about this in the Hula Hooping tribe. If you go there and open up the description, you'll find links to all the discussions on this topic. I'm not sure Natasha wants these kind of discussions here since this tribe is dedicated to "video" tutorials.

I can tell you that I don't like anything in my hoops. That messes up the rotation, especially for hand hooping. Instead, to make a hoop heavier, I recommend using a heavier psi (160 is good) or applying multiple rows of tape, which also makes a hoop heavier but in a very balanced way.

1 inch, 160 psi is heavier than 3/4, 160 psi. PSI refers to pounds per square inch, how much pressure the pipe can hold before bursting. It indicates how thick the walls of the pipe are. 1 inch is heavier because it's bigger around but I find that too big for my hand. I prefer to be able to easily close my hand around the tubing so I use 3/4" or even 1/2" tubing.

Hope this helps. Check out the Hula Hooping tribe. Lots more info there!

Like Caroleena said, putting anything inside the hoop messes up the rotation. My friend accidentally bought 3/4 in 100psi, which was much lighter than we were used to. We tried putting water in one of them and it was just a goofy mess! I, like Caroleeena, suggest 3/4 in 160psi. I think they're the perfect size and weight. Good luck!