- oxygenation of the water of the water
- Maintains even water temperature
- Promotes beneficial bacteria growth
- Moves debris to filter intake
- Provides currents for fish
Another key benefit of good water movement is maintaining even water temperature. If there is little or no water movement, zones of warm and cold water will quickly arise. Circulating the water will prevent temperature layering from occurring. Using small power heads in different locations, or spray bars will go a long ways towards evening out the aquarium water temperature.
When water movement is decreased, it is not uncommon for nook and crannies within the tank to become essentially 'dead zones'. Debris will collect in these areas, and over time can even impact beneficial bacterial colonies, not to mention become an eye sore. Directing water flow in these dead areas will move the debris around so it is eventually captured by the filtration system.
Last, but certainly not least, water movement is important to many species of fish. In fact, some fish require a current for optimal health. However, the converse is true for some fish. Bettas, for instance, prefer calm water with little movement. Always study the needs of your fish, and increase water movement for only those species that need it.
Placing a powerhead near the heater will help drive heated water to other parts of the tank. In a tank without sufficient water movement, cool water will remain in the lower regions of the tank, while warmer water rises to the upper strata. Water movement will ensure that the water temperature in the aquarium is fairly even across all levels within the tank.
In large tanks several powerheads may be utilized to avoid dead spots within the tank that can occur. Even in smaller aquariums, a nano powerhead can serve a beneficial purpose, by keeping the water circulating evenly throughout the tank.
Generally filters or powerheads that can be used with a spray bar, will include one in the package. However, if one is not included, becomes clogged or worn out, it's fairly easy to create your own DIY spray bar. Simply cut a PVC pipe to the length needed, plug one end with an end cap, and drill small holes along the length of the pipe. Measure the filter or powerhead outlet to get the correct diameter tube, which generally is about three eights inch.