There are two main types of potometers: the bubble potometer (as detailed below), and the mass potometer. The mass potometer consists of a plant with its root submerged in a beaker. This beaker is then placed on a digital balance; readings can be made to determine the amount of water lost by the plant. The Limitations in using the potometer: Introducing the air bubbles is not very easy. The twig may not remain for a long time. Any change in the outside air temperature may affect the position of the air bubble on the capillary tube.