Compressed-air aeration offers a simple and inexpensive way to dramatically improve water quality in larger ponds. A compressor outside the pond pumps air through small diameter hoses to a weighted diffuser located at the bottom of the pond. The diffuser generates millions of air bubbles each minute; as these bubbles float to surface, they carry water with them. When this water reaches the surface it spreads outward, allowing dissolved gases in the water to escape into the atmosphere and oxygen in the atmosphere to diffuse into the water. Since this aerated water came from the bottom of the pond, it is colder than the surface water and gradually descends to the bottom of the pond where it drifts towards the diffuser and completes the circulation loop. Larger ponds may require multiple compressors and diffusers, depending on depth and shape. This process can move millions of gallons of water daily using only a tiny fraction of the energy that would be required to pump the same volume.
simple aeration system with
compressor, diffuser, and air hose
circulation loop with an aeration system
LINEAR COMPRESSORS: PondTechnology linear compressors are extraordinarily quiet and energy-efficient, so they are the compressor of choice for shallow ponds. We offer two models: PA04 (1.7 cfm and 35 watts at 4 ft depth) is normally used with a single diffuser when ponds are 3 ft to 6 ft deep and two diffusers when ponds are less than 3 ft deep; PA08 (3.2 cfm and 80 watts at 4 ft depth) is normally used with two diffusers when ponds are 3 ft to 6 ft deep and four diffusers when ponds are less than 3 ft deep. Both compressors are enclosed in water-resistant cast aluminum enclosures suitable for exterior use provided they are mounted above the high water level of the pond in a location that can never flood.
ROCKING-PISTON COMPRESSORS: PondTechnology rocking piston compressors are recommended for ponds too deep for our linear compressors because they are efficient, reliable, and quieter than most other high-pressure compressors. Our rocking piston compressor PA20 (1.8 cfm and 240 watts at 20 ft depth) can operate a diffuser at depths up to one hundred feet with thousands of feet of hose! This type of compressor cannot be exposed to the elements and requires some sound shielding, so it should be installed in a garage, shed, or other out-building at a height above the high water level of the pond.
SELF-SINKING AIR HOSE: When ordinary hose is used to deliver air from a compressor to a diffuser, it floats to the water surface. One solution is to tie bricks onto aeration hose, but the hose still floats in between the bricks, and the bricks eventually deteriorate. A better solution is to use our self-sinking air hose, a heavy wall black tubing made from a very dense PVC compound. This tubing stays neatly on the pond bottom without the need for ballast, and is extraordinarily tough and abuse resistant. We normally supply 5/8" ID since the large cross-section assures there will be virtually no pressure loss even with more than one thousand feet of hose. We stock 25 ft, 50 ft, and 100 ft lengths; for longer runs, 100 ft lengths can be joined with our barbed couplings and heavy-duty stainless-steel hose clamps.
weighted diffuser assembly
WEIGHTED DIFFUSER ASSEMBLY: Our weighted diffuser assembly consists of a disc diffuser mounted on a 2 ft diameter black plastic base. The base is hydrodynamically designed to minimize turbulence and reduce bottom scouring, and it contains an internal cavity that is filled with ballast to prevent floating. The air hose from the compressor passes through a side port and connects to a hose fitting attached to the underside of the disc diffuser. The diffuser contains a 9" diameter black EPDM rubber disc with thousands of tiny slits that form a series of concentric circles: when compressed air enters the cavity behind this rubber disc, the disc expands to form a dome, the slits expand, and air escapes as tiny bubbles. Disc diffusers are more reliable and require less maintenance than diffusers using porous ceramics or plastics because rubber discs last for many years and clean themselves each time they expand.
DESIGNING AN AERATION SYSTEM: The following chart can be used to determine the zone of aeration for each diffuser based on depth. To design an aeration system, simply layout on a drawing of the pond or lake a series of circles with a diameter corresponding to the water depth at the center of each circle. Note that deep ponds require fewer diffusers than shallow ponds because each diffuser creates a larger circulating loop. As a consequence, a single diffuser may suffice for a deep one-acre farm pond whereas multiple diffusers may be required for a shallow backyard pond!
|Zone of Aeration at Different Diffuser Depths|
|2 ft||25 ft||500 sq ft||1/80 ac|
|4 ft||50 ft||2,000 sq ft||1/20 ac|
|6 ft||75 ft||5,000 sq ft||1/8 ac|
|8 ft||100 ft||10,000 sq ft||1/4 ac|
|12 ft||150 ft||20,000 sq ft||1/2 ac|
|16 ft||200 ft||40,000 sq ft||1 ac|
|20 ft||250 ft||60,000 sq ft||1-1/2 ac|
|24 ft||300 ft||80,000 sq ft||2 ac|
When multiple diffusers are operated by the same air pump, they must be installed at the same depth to assure equal air distribution. We will supply a valve manifold for final balancing.
Linear Compressor, for 1-2 diffusers - $160.00
Linear Compressor, for 2-4 diffusers - $240.00
Rocking-Piston Compressor, for 1 diffuser - $396.00
Self-Sinking Air Hose, 25 ft - $36.00
Self-Sinking Air Hose, 50 ft - $68.00
Self-Sinking Air Hose, 100 ft - $132.00
Disc Diffuser With Weighted Base - $120.00