Whirlpools are characterised by having jets to the side of the bath about midway up in conjunction with a suction point (similar to be able to colander) within the bottom four corners. This type of system produces hydro-massage by sucking water from the bathtub and pumping it off the jets quietly under stress and strain. To increase the pressure for this jets most whirlpools have a control on the top of the bath which allows air in order to sucked into the jet of water. You must get acquainte...