An apparatus for treating tissue with ultrasound, the apparatus comprising: a probe including a transducer which is positionable proximate to the tissue, the transducer being configured to image tissue by emitting and sensing ultrasound energy and to treat tissue by emitting ultrasound energy, a positioning member coupled to the transducer and configured to position the transducer relative to the tissue, and a fluid inlet and a fluid outlet, both the fluid inlet and the fluid outlet being in fluid communication with a fluid pathway including an area adjacent a face of the transducer; and a fluid circulation system in fluid communication with the fluid inlet and the fluid outlet of the probe, the fluid circulation system including a pump configured to circulate a fluid throughout the fluid circulation system and the fluid pathway of the probe; a chiller configured to reduce a temperature of the fluid; a degasser which is configured to remove dissolved gases from the fluid; a fluid adjustment member including a fluid reservoir in which the fluid passes, the fluid adjustment member being configured to both add additional fluid to the fluid circulation system and remove fluid from the fluid circulation system, the fluid adjustment member being in fluid communication with the reservoir; and a first fluid circuit being in fluid communication with the fluid pathway of the probe, the pump and the reservoir characterized in that there is a second fluid circuit being in fluid communication with the degasser and the reservoir such that fluid in the second circuit may pass into the first circuit through the reservoir and fluid in the first circuit may pass into the second circuit through the reservoir, and a second pump is a part of the second circuit, the second pump configured to circulate the fluid through the second circuit. a probe including a transducer which is positionable proximate to the tissue, the transducer being configured to image tissue by emitting and sensing ultrasound energy and to treat tissue by emitting ultrasound energy, a positioning member coupled to the transducer and configured to position the transducer relative to the tissue, and a fluid inlet and a fluid outlet, both the fluid inlet and the fluid outlet being in fluid communication with a fluid pathway including an area adjacent a face of the transducer; and a transducer which is positionable proximate to the tissue, the transducer being configured to image tissue by emitting and sensing ultrasound energy and to treat tissue by emitting ultrasound energy, a positioning member coupled to the transducer and configured to position the transducer relative to the tissue, and a fluid inlet and a fluid outlet, both the fluid inlet and the fluid outlet being in fluid communication with a fluid pathway including an area adjacent a face of the transducer; and a fluid circulation system in fluid communication with the fluid inlet and the fluid outlet of the probe, the fluid circulation system including a pump configured to circulate a fluid throughout the fluid circulation system and the fluid pathway of the probe; a chiller configured to reduce a temperature of the fluid; a degasser which is configured to remove dissolved gases from the fluid; a fluid adjustment member including a fluid reservoir in which the fluid passes, the fluid adjustment member being configured to both add additional fluid to the fluid circulation system and remove fluid from the fluid circulation system, the fluid adjustment member being in fluid communication with the reservoir; and a first fluid circuit being in fluid communication with the fluid pathway of the probe, the pump and the reservoir characterized in that there is a second fluid circuit being in fluid communication with the degasser and the reservoir such that fluid in the second circuit may pass into the first circuit through the reservoir and fluid in the first circuit may pass into the second circuit through the reservoir, and a second pump is a part of the second circuit, the second pump configured to circulate the fluid through the second circuit. a pump configured to circulate a fluid throughout the fluid circulation system and the fluid pathway of the probe; a chiller configured to reduce a temperature of the fluid; a degasser which is configured to remove dissolved gases from the fluid; a fluid adjustment member including a fluid reservoir in which the fluid passes, the fluid adjustment member being configured to both add additional fluid to the fluid circulation system and remove fluid from the fluid circulation system, the fluid adjustment member being in fluid communication with the reservoir; and a first fluid circuit being in fluid communication with the fluid pathway of the probe, the pump and the reservoir characterized in that there is a second fluid circuit being in fluid communication with the degasser and the reservoir such that fluid in the second circuit may pass into the first circuit through the reservoir and fluid in the first circuit may pass into the second circuit through the reservoir, and a second pump is a part of the second circuit, the second pump configured to circulate the fluid through the second circuit.