Pot saucers go underneath your hydroponics pot to catch any excess water or nutrient solution. If you are using a recirculating hydroponic system, the nutrient solution can be drained from the saucer back into a reservoir. It is then pumped from the reservoir to the plants in a continuous cycle. For a run to waste hydroponic system, the nutrient solution simple runs off into the saucer and is discarded. RhizoStands and Drainaway Trays are types of saucers which come complete with inbuilt drainage holes and fittings.