Abstract: Hydroponic nutrient solution is fed to a growing bed by means of a pump withdrawing liquid nutrient solution from a supply reservoir located below the bed. The nutrient solution is rapidly drained from the bed when the pump is de-energized through a dump valve having no moving parts which bypasses the solution draining from the bed directly into the supply reservoir. The dump valve consists of a hollow body having at least one drain aperture. A stream of nutrient solution under pressure passes through a nozzle in the inlet of the valve body and is discharged into the outlet of the valve body. When the pump is de-energized, a major portion of the solution draining from the growing bed passes through the aperture and drains directly into the reservoir.