Surface aeration is intended for ponds less than seven feet in average depth. A pump is suspended from the surface of the water via a float, which is tied to the shore or to cinder blocks at the bottom of the pond.
When purchasing a floating fountain, one of the benefits is the aeration these can do for your pond. Without aeration, muck buildup at the bottom of the pond increases and sends noxious gas bubbles to the surface, resulting in algae blooms and stink. It is super important your pond stay oxygenated for ecological balance. Oxygen needs to be dissolved throughout the pond to decrease stratification (layering) of pond water at different depths. A balanced pond is healthy for fish and will reduce algae buildup, stagnation, and mosquito reproduction.
There are three kinds of surface aeration:
Decorative Fountain Aeration--Decorative fountains use pumps with impellers to send water through a nozzle. There are dozens of brands of decorative fountains, and they differ greatly in how much aeration they provide. You see, the nozzle greatly affects flow volume, which is the major marker of how much aeration will take place. Some nozzles place great restrictions on flow volume by including small holes to achieve great heights and widths. Think of it the way you would restrict flow from a garden hose. The water will squirt further with more restriction, but total flow volume will be reduced. So when it comes to deciding on which fountain to purchase, you will need to decide how much emphasis you want to place on aeration and how much on aesthetics.
Aerating Pond Fountains--The pumps for these fountains will aerate more than a decorative fountain. The pumps use propellors instead of impellers and the flow typically is not restricted by a nozzle. Rather, the angle and shape of the propeller creates a V-pattern. As far as balancing aesthetics and aeration, these are the best choice.
Surface Aerators-- Surface aerators also use a propeller but they produce the most aeration of the three types of surface aerators. Display from these is minimal, just large bubbles at the surface of the pond, though if illuminated at night with LED lights they can still add beauty to your pond or lake. This is the best choice if your primary concern is aeration.
Horsepower Does Not Equal Aeration
There is quite a difference between brands when it comes to aeration. Horsepower of the pump is not what is most important, but the volume of water being recirculated in your pond. Companies that manufacture fountains that reach great heights tend to use smaller holes in their nozzles, which means that less water is being recirculated in the pond. The smaller holes restrict water flow. Pond fountains made by Kasco provide the best aeration.
Kasco Marine provides, in our opinion, the best flow of any surface aerators. You will notice in closeups of water discharging from the nozzles (in the case of their JF, decorative fountain line) that Kasco products provide ultimate water circulation. Their JF nozzles have large holes so more water is pumped out of the nozzles. The VFX line (their aerating fountains) uses a propeller for ultimate aeration of a fountain.
Closeup of Kasco Nozzle, JF Decorative Series
Closeup of Kasco VFX, Aerating Fountain
A Final Note for Ponds Deeper than Seven Feet
To aerate deeply into the water, you will need to use a bottom aeration (diffuser) system. A compressor is mounted at the shore and is connected to tubing that is connected to a diffuser or set of diffusers at the bottom of your pond or lake. Surface aerators do not reach great depths so aeration needs to be done from the bottom up. However, if you still want a display, you can combine the two: using a diffuser for aeration and a decorative pond fountain for display.
We sell many brands of fountains, but as far as aeration goes, we recommend Kasco as the best on the market.