As seen from the name a submersible is a pump that completely submerges under water. A submersible pump is used for many situations, for example submersible pumps are often used to pump out overflowed crawl spaces and basements. Because the pump in a submersible pump is at the bottom the liquid can be pumped up to any desired height. Irrigation systems also need submersible pumps, in this case the submersible pump is to be placed on the bottom of your nutrient vessel and used to pump water up. We sell submersible pumps of the brands AquaKing, DAB and RP. Some submersible pumps come with a float switch, this is a part of a controller that floats on the water and keeps track of the water level and ensures that the submersible pump will not run dry.