We use them all the time.
GREAT SELLER!
Sometimes, just an inch or so in the bottom of a clear glass cylinder bowl, with a flower or two floating on top (Note: too little water, and there is not enough for the flower to drink. To much, and the beads will look like tapioca pudding gone bad.))
We sell an arrangement called Fire and Ice. Fill a vase 2/3 full, and float candles on top. Cheap, sellable, and still beautiful.
I did a 70's disco theme party, filled a clear vase 3/4 full with beads, then then submerged a few cloured light cubes underwater. Floated a giant dahlia on top, in neon colours. WOW.
If you use HOT water, the beads will grow bigger. We prepare them before going home in giant tupperware containers,...next morning they are ready to go. Any extra, or any that come back we store in the cooler till the next party, and put an arrangement into the shop , showing how to use them to sell the individual packs.
TIP: We re-package the beads into little jars from the dollar store, and put custom printed labels onto them. It allows us to mark up the price more, and we rename the beads so it loks like a custom product. Great way to make an extra buck.
Last year we sold over a thousand little jars at 7.50 each.
Try it. It has worked for us.