Control system for periodically feeding nutrient solutions to hydroponic plant beds

Claim 1

In a hydroponic system comprising at least one plant bed and a storage vat means, electric pump means connected between said plant bed and said storage vat means for pumping nutrient solution To said plant bed from said storage vat means, means connected to said vat means for replenishing lost water to said vat means and including a solenoid-operated valve, the improvement comprising: a first clock switch means electrically connected to said pump means for periodically energizing said pump means, said first clock means being adjustable as to the time and the duration of each pumping cycle, a second clock switch means electrically connected to said first clock switch means and adapted to disable said first clock switch means adjustably between near sunset and near sunrise times, said second clock switch means being further augmented by means for permitting opening of said solenoid valve only during the time said first clock switch means is disabled by said second clock switch means, whereby said storage vat means is protected against possible overflowing by back drainage from a recently flooded bed into an already full vat means.