No, you CAN
buy vinyl tubing to fit over the AquaStops on Fluval canisters. I did just that on my Fluval 106, which uses the same OD/ID (outer diameter / inner diameter) as the 206. The 306/406 are larger.
Here's the tubing and the lily pipes & aquastops... The OD is 5/8" and the ID is 1/2"
... this results in it being compatible with 13mm lily pipes.
Here's the fit over the aquastops... very hard to get on but doable. Just need to heat up a tub of water to put the ends of the hose in or use a heat gun to get the vinyl hose soft enough to force over the aquastops. But once over, it formed a tight seal.
As shown here:
And to the lily pipes: