PROBLEM TO BE SOLVED: To provide a water quality adjusting system smoothly controlling the pH of liquid to always keep in a stable state without changing liquid or using medicine such as a pH adjuster. SOLUTION: This water quality adjusting system for disinfecting purifying liquid 5 such as nutritious liquid, stored in a liquid tank 2 and circulating on an outside line 4 includes a disinfecting purifying unit 3 having an ozone supplying portion 15 supplying ozone to the liquid 5, an ultraviolet ray emitting portion 16 for emitting ultraviolet rays, and a photocatalyst activating portion 17 activating photocatalyst, and a pH sensor 10 measuring the pH of the liquid 5. The pH of the liquid 5 is made close to a previously fixed set value by activating either one or a plurality of the ozone supplying portion 15, the ultraviolet ray emitting portion 16, and the photocatalyst activating portion 17, based on the pH of the liquid 5 measured with the pH sensor 10. COPYRIGHT: (C)2011,JPO&INPIT
