I use suction cups on the glass. You can buy clear suction cups at an arts supply store; the type use to hang bobbles in windows. I then cut the bamboo about 1/4" shorter than the inside glass to glass dimension. Place one suction cup on the glass on one side. The cups have a little nib/knob on them for the hanger (don't use the metal hanger). Put the hollow end of the bamboo over the suction cup. Place the other suction cup inside the other end of the bamboo with the knob inside the bamboo and the cupped portion out. Wet the glass on the other end of the tank and slowly move the bamboo into place. The wet galss allows you to slide the suction cup about until it is in place. This holds nicely even for my grandis. You can get the suction cups in several sizes to use different size bamboo. It gives a nice clean look and allows you to adjust the height and location of the bamboo.
If you don't have glass surfaces then try velcro. use a circle of vecro on the surface oyu want ot put the bamboo and then plug the hollow end of the bamboo with place and stick the velcro over the end (cover the plugged hole). Only with velco you have to cut the bamboo very close to the right size and once in place it is very difficult (but not impossible) to remove the bamboo.
I have also used cork background to hold bamboo horizontally. On one side use a hole saw to make a hole in the cork to accept the bamboo. On the other side use a suction cup or take a peice of cork with a hole in it big enough for the bamboo and slide it over the end of the bamboo. Then with the bamboo in place, glue or silicone the cork to the wall/side of the tank so it hold up the bamboo.
Lastly you can silicon the bamboo in place, but removal requires a razor blade and patience.
Regards,
John