I use airline tubing siphon to clean out the poop in between the shells in my shell dweller tank, but the airline hose wont stay straight enough to direct it. This is how I solved it: I slipped the piece of tubing inside a regular drinking straw! it worked great! I thought you all might be able to use this tip, there always seems to be a need for a small piece of straight tubing. I found I could also slide 2 straws on and make it longer.
I had to use a bendable straw and discovered that the bend in the straw, when slid down over the end of the tube made a nice angle for those hard to reach spots. The siphon functioned normally because the straw fit snugly on the tubing. If you have a larger straw, you may need to tape the straw to the tube to get a tight seal. You don't need to worry about suction if you are just using the straw to stiffen the tubing. I found that it worked best with the heavier tubing, the very flexible tubing was hard to fit the straw on, but the straw fit tightly and made a handy dandy little extension.