Aeration is all about gasses. Aeration mixes the pond so toxic gasses are efficiently released and life-giving oxygen readily replaces it. An aerated pond will be clearer, cleaner, and have less bottom muck than a pond without aeration.

1. Stratification  A pond without aeration will become stratified into two very separate layers in the summer heat. The warmer surface water becomes less dense and lighter than the cool water below it. The line at which these two layers separate is called the thermocline. Aeration prevents the water stratification.
2. No Oxygen = No Life  The vast majority of water-cleaning organisms (aerobic bacteria & phytoplankton) in a pond use oxygen to drive their metabolic processes. Oxygen enters the water column almost exclusively through the surface of a non-aerated pond. Because the surface water does not mix with the water below, oxygen in the bottom layer quickly becomes depleted under stratified conditions, allowing toxic gasses to build up. Because no oxygen is available below, the pond’s overall ecosystem will begin to suffer.
3. Nutrient Build-Up   Without water-cleaning organisms on the bottom, any sediment, debris, and nutrients that enter the system fall to the bottom and accumulate. An unwanted pile of muck and a toxic lower layer in your pond will quickly cause major headaches, including algae blooms, rampant weed growth, and fish kills.

Fountains are a great way to add visual appeal to your pond. Fountains also add a great deal of oxygen to the pond as the tiny droplets make contact with the air and fall back into the pond. But do pond water fountains provide enough aeration? Like choosing an aeration system, determining if a fountain is right for your pond depends on the depth, shape, and size.

Six Foot Rule

If your pond is more than 6 feet deep, a fountain will not provide enough aeration. Why? Proper pond aeration is achieved when the entire body of water circulates simultaneously. Fountains only draw water from the top of the water column, so the water deeper than the 6-foot mark remains untouched and oxygen-deprived.  Subsurface (bottom) aeration with weighted diffusor is recommended for deeper ponds to provide complete circulation. Air is pushed through diffuser plates positioned at the bottom of the pond. As the air bubbles rise, oxygenated water from the surface moves to the bottom, creating an aerobic pond ecosystem.

Significance of Shape

Bends and curves add a dramatic look to your pond, but they also restrict circulation. Multiple pond water fountains or a combination of a fountain and aeration system may be needed for uniquely shaped ponds. You cannot over-aerate a pond, but you can under aerate it leading to more weed and algae growth in the areas that are not getting enough oxygen.

Other Considerations

It is recommended to remove fountains for the winter to prevent damage during icy conditions leaving your fish without oxygen.  Additionally, a fountain can get costly when operating it 24/7. An aeration system is designed to be used in the chilly winter months and is an affordable alternative as it has lower operating costs.