A water level controller for a hydroponic system, the water level controller comprising:
- a hollow casing which is fixed in a hydroponic cultivation tank;
- a float which is pivoted in the casing to ascend and descend with a water level of a culture solution, wherein a bottom of the hollow casing is connected with the hydroponic cultivation tank, a top of the hollow casing is connected with atmosphere, and the hollow casing is provided with an inlet valve and two first magnetic attraction elements, wherein one first magnetic attraction element is disposed on a side of the hollow casing, the side extending between the top and the bottom of the hollow casing, an other first magnetic attraction element is disposed on the top or the bottom of the hollow casing, the inlet valve is provided with a water inlet end for feeding in the culture solution from outside and an inlet nozzle which is transfixed into the hollow casing, allowing an outer culture solution to enter the hydroponic cultivation tank through the inlet valve to raise the water level;
- a side of the float being pivoted in the hollow casing, so that an other side of the float shifts upward and downward with the culture solution against the pivot point, and the float being further provided with two second magnetic attraction elements and a seal which shift with the float simultaneously;
- the seal being disposed on a location corresponding to the inlet nozzle of the inlet valve to abut at and close the inlet nozzle of the inlet valve when the water level in the hydroponic cultivation tank ascends to a high water level, whereas the seal moves away from the inlet valve when the water level descends to a low water level;
- the two second magnetic attraction elements being disposed on the float at locations corresponding to the two first magnetic attraction elements, with one second magnetic attraction element of the two second magnetic attraction elements shifting with the float simultaneously to approach and attract a corresponding one first magnetic attraction element of the two first magnetic attraction elements to keep the seal closing the inlet valve when the high water level is reached, until the water level in the hydroponic cultivation tank descends to the low water level such that a force of gravity of the float is larger than a force of magnetic attraction between the one second magnetic attraction element of the two second magnetic attraction elements and the one first magnetic attraction element of the two first magnetic attraction elements, enabling the one second magnetic attraction element of the two second magnetic attraction elements to escape from the one first magnetic attraction element of the two first magnetic attraction elements;
- and
- an other second magnetic attraction element of the two second magnetic attraction elements shifting with the float simultaneously to approach and attract a corresponding other first magnetic attraction element of the two first magnetic attraction elements to keep the seal moving away from the inlet valve when the low water level is reached, until the water level in the hydroponic cultivation tank ascends to the high water level such that the buoyancy force of the float is larger than a force of magnetic attraction between the other second magnetic attraction element of the two second magnetic attraction elements and the other first magnetic attraction element of the two first magnetic attraction elements, enabling the other second magnetic attraction element of the two second magnetic attraction elements to escape from the other first magnetic attraction element of the two first magnetic attraction elements.