Although not offered by several manufacturers (but a standard feature on a few others), an air bubbling system adds a little fun to your hot tub, which is one of the reasons to purchase a hot tub in the first place. If you have children, this option should be seriously considered because kids love the bubbles! Look for a system that creates bubbles by utilizing the warm air created by the tub's motor. Avoid systems that utilize cold air brought in from the outside of the tub - this will lower your water temperature very quickly and cost you more to heat your hot tub.