I get many questions every week as to the nature of fountains vs diffused aerators. They are different, they perform different tasks, and most often it matters witch one you choose.....
All fountain manufactures (and I do mean ALL FOUNTAIN MANUFACTURES) market their products as aerators. They are correct in the abstract, but fall short in the task of true whole pond aeration.
By definition, the aeration of water is the agitation of surface water or the infusion of atmospheric air (or oxygen) into the water column. So yeah, they do aerate the water. The difference is in how they do it and their effectiveness in doing so. Aerating fountains have been the staple management tool for fish hatcheries world wide for half a century. They will aerate the water column and keep your fish happy and healthy.
Fountains float on the surface of the water and shoot water into the air creating a fantastic display, and most times they even have lights attached to enhance the experience at night (fountain)(lights). I do love me my fountains, they truly enhance the pond atmosphere and cancel out traffic noise and do turn some air into the pond. They are very good at forcing floating debris, algae, and plants like duckweed to the edges of the pond where they can be more easily removed/treated.
For best management results: these units are best suited for ponds that are 4-5ft deep (or less). Fountains can only suck water from around where they are floating, so you are only mixing the water within the first 3-4ft of water depth. For systems deeper than 4-5ft and larger than 7000 square feet you need a diffused aeration system.
Sub-suface diffused aeration systems are comprised of an air compressor, airline, and diffusers.
The diffusers sit on the bottom of the pond and "diffuse" billions of bubbles witch rise to the surface. The overall size of the pond determines how many diffusers you will need to adequately turn over the pond.
Diffused air does more than just inject oxygen into the water, it also removes the bad dissolved gasses (methane, ammonia, nitrous oxide, sulfur dioxide) as the oxygen moves out of the bubbles and into the water, these bad gases move in and are carried to the surface where they blow away on the wind. The surface area of the bubbles also grab all of the water around them and lift it to the surface. This effectively turns the pond over and exposes the nutrient rich water from the bottom to the atmosphere, releasing even more bad gases and turning in more air. These systems also are necessary for the degradation and decomposition of organic soft sediment (muck) as they provide oxygen to the bottom sediments allowing for the bugs and microbes to consume the organic material. Example of a good system (here)
So, long story short...... If you are looking to turn some water and have a beautiful display...... the Fountain is the way to go.
If you are looking to manage an aquatic ecosystem, and help the overall health and longevity of a pond the diffused aeration system is the correct option.
If you desire both.... well then by all means, install them together and enjoy your pond for years to come.
Thanks so much for reading..... please contact me if you want some clarification or a more in depth review of these systems. CSJ&J Gardens and midwestponds.com 920-205-4560.