Circulating irrigation systems are typically kept relative small. One system can handle 2-5 lettuce lines. The purpose of this is to minimize the risk of deceases and to enable the use of different mixtures of fertilizers. One system consists of return water tanks, pump, filtration and cleaning system, fertilization control system, irrigation piping, drip emitters and return water chutes and piping. Cooling system is also possible (circulating the return water trough cooling system).
In the irrigation system the water is dosed to the gutters from pressure compensated drip emitters. Water flows from the gutters to the circulation water tanks, which are placed under the growing line. From the tanks the water is pumped to the fully automatic filtration system. Pressure difference is monitored and the cleaning cycle is done automatically only when needed. Cleaning of the filtration system is done with fresh water. This saves fertilizers and extra nutrients doesn’t burden the environment. All parts of the system are located under the growing lines. Extra constructions to the greenhouse is not needed.