Full-automatic timed water exchanger

The invention relates to the technical field of automatic water changing, particularly to a full-automatic timed water exchanger. A machine body is divided into the upper portion and the lower portion; a water drainage starting barrel, a water adding barrel and a casing are installed on a support of the upper portion of the machine body in a side by side mode; a water adding complementary starting barrel is arranged above the water adding barrel; a water drainage barrel, a water adding starting barrel and a casing are installed on an upper section of the support of the lower portion of the machine body; a water inlet pipe which is connected with a filter and a flexible cover plate are installed on a lower section of the support; a four way pipe and a timed water valve are connected to the lower section through a T-branch pipe; and a complementary water adding water valve, a water inlet water valve of a floating ball water adding valve and a complementary water drainage water valve are respectively arranged on