An aquatic exercise facility for animals including a pool of water having an animal entry area and an animal exit area in alignment with a portion of the pool therebetween of a depth sufficient to require the animal to swim thereacross, mechanism for pumping water to establish a current from the animal exit area toward the animal entry area, the pumping mechanism having an inlet and an outlet for water thereto and a control for controlling the amount of water pumped thereby, a return channel for water disposed on either side of the pool for returning water from the animal entry area to the inlet to the pumping mechanism, and adjustable flow control structure disposed between the deep portion of the pool and the return channels for adjusting the rate of flow of water therebetween; also disclosed are directing vanes at the outlets from the pumping mechanism to direct the current to provide a higher velocity along the sides of the pool than in the middle thereof; there further is disclosed an improved water filtration and treatment system for use with such facilities as well as an improved channel structure.