Depending on the thickness of the tubing wall, the time necessary to get the tubing "pliable"will vary. Experiment a bit! Once you have the tubing soft, remove it from the water and commence wrapping it around your cylinder. Work quickly as your tubing will cool very fast! Use duct tape or similar to hold your coils in place. You may have to use several "segments" before you get the entire length completed. These lengths can be connected with vinyl hose later. Keep the coils tight together and as they cool, they should retain their new shape.
Remove the coil from the the cylinder form and insert the coil INSIDE the cylinder. Run a piece of tape down the inside of the coils. Remove the taped coil from the cylinder. You can now daub silicone in between the coils. You don't need to do any of the tape and and glue thing. If you have already attached the bottom to your cylinder, just work the coils into the unit and continue your final assembly.