Disclosed is a disposable for use with a structure having a vessel surface that defines a vessel for receiving liquid. The disposable includes a pad and a layer. The pad has a pair of surfaces spaced apart from one another by a tubular sidewall. The pad is permeable to air flow. One of the pair of surfaces is positioned, in use, against the vessel surface. The layer overlies the other of the pair of surfaces and is at least substantially impermeable to air flow. In use, gas is introduced into the pad and issues through the sidewall in the form of bubbles. The disposable is useful in association with foot spas and the like.