a bubbler is a water culture hydroponic setup. plants are suspended over a water and nutrient reservoir in baskets with a soilless medium. The roots grow down into the water that is being aerated by bubbles produced by air pumps and air stones. The oxygen from the bubbles dissolves into the the water. The roots uptake oxygen, water, and nutrients simultaneously and provide for very explosive growth.
search these terms: DWC, Deep Water Culture, RDWC, Recirculating Deep Water Culture, SWC, Shallow Water Culture