A pump comprising: a body which defines an inlet and an outlet to allow flow of a liquid, wherein the pump has a suction side around the inlet and a pressure side around the outlet; an impeller positioned downstream of the inlet; a backflow opening in fluid communication with the inlet and the outlet; and a first valve operatively coupled with the backflow opening to selectively open the backflow opening, wherein the first valve defines a first end and a second end, and wherein the first valve includes a first valve housing, wherein a first valve body is biasingly coupled by a first spring within the first valve housing around the second end, and wherein the first valve body is adapted to move the first spring to a first compressed state to disallow flow of the liquid through the first valve, and the first valve body is adapted to move the first spring to a first uncompressed state to allow flow of the liquid through the first valve; characterized in that: a second valve disposed within the first valve, wherein the second valve has a second valve body, wherein the second valve body is biasingly coupled by a second spring within the first valve body, wherein the second valve body is adapted to move the second spring to a second compressed state to allow flow of the liquid through the second valve, and the second valve body is adapted to move the second spring to a second uncompressed state to disallow flow of the liquid through the second valve. a body which defines an inlet and an outlet to allow flow of a liquid, wherein the pump has a suction side around the inlet and a pressure side around the outlet; an impeller positioned downstream of the inlet; a backflow opening in fluid communication with the inlet and the outlet; and a first valve operatively coupled with the backflow opening to selectively open the backflow opening, wherein the first valve defines a first end and a second end, and wherein the first valve includes a first valve housing, wherein a first valve body is biasingly coupled by a first spring within the first valve housing around the second end, and wherein the first valve body is adapted to move the first spring to a first compressed state to disallow flow of the liquid through the first valve, and the first valve body is adapted to move the first spring to a first uncompressed state to allow flow of the liquid through the first valve; characterized in that: a second valve disposed within the first valve, wherein the second valve has a second valve body, wherein the second valve body is biasingly coupled by a second spring within the first valve body, wherein the second valve body is adapted to move the second spring to a second compressed state to allow flow of the liquid through the second valve, and the second valve body is adapted to move the second spring to a second uncompressed state to disallow flow of the liquid through the second valve. a second valve disposed within the first valve, wherein the second valve has a second valve body, wherein the second valve body is biasingly coupled by a second spring within the first valve body, wherein the second valve body is adapted to move the second spring to a second compressed state to allow flow of the liquid through the second valve, and the second valve body is adapted to move the second spring to a second uncompressed state to disallow flow of the liquid through the second valve.