Unplug the fountain's power cord. Remove the housing that conceals the fountain pump, or remove the stones, shells or other material to access the pump.
Locate the flow control switch if the pump has one. Water fountains use submersible pumps designed for safe operation in water. The flow rate switch is usually a button that slides from side to side or a recessed dial located on one side of the pump's housing. An "S" indicates slow, and "F" is for fast.
Move the switch or dial to the "S" position. If your fountain pump doesn't have a flow rate adjustment switch, it will only operate at one flow rate. If it has a tube, removing the tube can give the fountain a softer sound. Grasp the tube firmly right above the pump housing and pull it out. If you remove the tube, refill the fountain to a lower water level so there's only 1/2 inch to 1 inch of water above the fountain pump.
Add or remove water if needed to adjust the fountain's water level. Scooping out water with a cup will reduce the water level for tubeless operation. Replace the housing or other items to conceal the pump.
Plug the fountain pump back in.