I don't use the tubes, but I have put HF beads in pantyhose and stuck that in a humidifier I had ripped the floral foam out of. I used "sheer", but I believe you could use most colors, as they are all pretty transparent when you stretch them out.
As for brand, whatever tickles your fancy I'd assume. My lady had an extra pair lying around so I wasn't picky.
Additionally: I take it you just poured DW on your beads? Or dunked them to add the DW? From what I've read, spraying was recommended for beads in containers, and I use the little dropper tool to add DW slowly to the beads - it will help keep them from fracturing, turning into crumbs, and making a mess in the humidor.