Barbed Anti Syphon Valve 13mm 

Barbed Anti Syphon Valve 13mm

These handy valves are normally used with dripper systems and reduce the chance of syphoning when the pump stops.
They work by allowing water to flow from the pump but when the pump stops, air can be suck into the pipe causing the syphon to stop.

Use
Attach the anti syphon valve to a 13mm tee using a small piece of flexi pipe, this is then attached to the pump using a length of flexi pipe, now the spare outlet of the tee can be attached to the flexi pipe which feeds the drippers.
It is important to locate the anti syphon valve within the nutrient reservoir but above the water level.