Aeration is essential for fish and general pond health. If fish don’t get enough oxygen, they will die. But even if you don’t have fish, without aeration, ponds create stratified layers, and the bottom layer is depleted of oxygen.
Ponds can also become shallower over time from a buildup of muck from a lack of oxygen. Plant materials need oxygen to steadily decompose, and if new plant life grows at a rate faster than old plants decompose (due to a lack of oxygen), muck accumulates at the bottom of the pond. This muck sends up gas bubbles, which can create a very foul smell resembling rotten eggs.
The most common type of aeration in large ponds is surface aeration. Surface aeration is also the pretty kind — in other words, a fountain is usually used. Typically, a propeller underneath the fountain agitates the water, decreasing stratification. In addition, water is forced into the air, ensuring that the pond is always being recirculated. The pond fountain motor usually sits underneath a float, which is then moored to the shore or the bottom of the pond.
The most efficient models provide no aesthetics, but merely create large bubbles at the surface. (Think of a sewer pond aerator.) Kasco Marine recommends a ½-Horsepower pump for every ½ acre of pond. Then there are aerating fountains, which provide some beauty balanced with a large volume of aeration. Kasco typically recommends 1 ½ Horsepower for every 1 acre of pond if you use one of these V-shaped fountains. Finally, there are decorative fountains, which provide the most versatility with regard to beauty, but offer less aeration. As a rule of thumb, Kasco Marine recommends 2 Horsepower for every 1 acre of pond.
For ponds that are more than 8 feet deep, bottom aeration is recommended. An air compressor is usually located at the shore, and a hose carries the air to a diffuser unit at the bottom of the pond. It is very similar to air bubbles rising from the bottom of an aquarium. Currently, there are many fairly quiet air compressors available for sale, and considering that they need to be housed to be protected from the elements, any associated noise is at a minimum.
If you have a deep pond but still want to see a fountain, you can combine surface and bottom aerators. The fountain would not need to aerate as much and could focus on the beauty aspect. This allows for a greater range of price as well as a dramatic view.
Some (but not all) manufacturers have tested their units for efficiency. One test measures Standard Oxygen Transfer Rate (SOTR) in pounds of oxygen per hour. Standard Aeration Efficiency, or SAE, is another measure, which calculates efficiency divided by power used. With all kinds of aeration, it is highly recommended that the customer make electrical calculations of operation before purchase, as manufacturers can vary considerably. Some aeration units use an incredible amount of energy, thus greatly increasing electric bills.
We get many requests for solar fountains. Though we wish we could give better news, these are still quite expensive. In 2020, expect to pay around $8,000 for a ½-acre unit. Also, the availability of sunlight limits their effectiveness. Fish need oxygen at night, too!
We also get a lot of interest in less expensive fountains. Several years ago, we started making our own line of less expensive pond fountains under the Fountain Tech brand name. These can provide a good option for homeowners on a budget, and our customers have been quite happy with them.
Michael Guista established Fountain Mountain as an online business in 1999. He incorporated the business and moved to a large warehouse in 2003. He’s been selling Kasco Marine products for nearly 20 years and started his own line of fountains 10 years ago.