"Think of it as something
similar to swishing your hand around in the bathtub," says Reanna Pelszynski,
general manager of Aqua Control in Peru, Illinois. "As the water moves around,
it helps even out the temperature and the oxygen concentration."
Aeration also provides the
oxygen necessary for aerobic digestion of algae, ammonia, and nitrites.
Bacteria aid in the decomposition of fish waste, debris, and other organic
matter; adding oxygen encourages this process. This protects fish health and
helps prevent dead organisms from accumulating as sludge in the lake or pond
bottom. It also helps eliminate pond odors.
In addition to improving
the chemical balance of the pond, circulating water can also push certain
kinds of algae to the sides of the pond where they can be more easily removed.
It can help control mosquito larvae as well, because mosquitoes do not breed
as freely in moving water.
In some climates, aeration
provides enough movement to keep the pond from freezing in winter months and
prevents winter fish kill by keeping the water oxygenated. Winter is a
critical time for pond health because a pond that is frozen over is deprived
of the oxygen it would normally get. Keeping a hole in the surface ensures
that the pond has continued access to oxygen throughout the winter. The open
water also helps provide a protected area for waterfowl.
There are several types of
aerators, and choosing the right one depends on the specifications of the pond
itself, the conditions you are treating, and the aesthetic look the homeowner
desires. "You need to take a variety of factors into account when you're
deciding on equipment and design," says Jerry Goldberg, vice president of
marketing and sales for AquaMaster Fountains and Aerators in Kiel, Wisconsin.
"These include the surface area, depth, shape, present water quality, and
water source. You also need to factor in the environment the pond is in and
the run-off that affects it."
Another important factor
to consider is what the pond will be used for. Is it a fish pond or a swimming
pond, or is it just for decoration? "You have to pay attention to the goal of
your clients," says Goldberg. "Are they primarily looking for the aesthetics
of a floating fountain, or are they looking for water quality improvement?"
For clients who are
looking for form as well as function, a floating fountain aerator can offer
the best of both worlds. Floating fountain systems float on the surface and
provide a fountain display in addition to aeration. Display aerators offer a
wide variety of spray patterns from subtle to majestic. They add curb appeal
and charm to the landscape while helping to improve pond health.
Floating surface aerators
also float on top but agitate the surface with a boiling effect instead of
providing a display pattern. These are an excellent choice where clients
prefer a low-profile aerator.
Aspiring aerators blow
oxygenated bubbles into the water, either from the surface down or from the
bottom up. If they are strong enough, the oxygenated water may penetrate to a
considerable depth, thus counteracting stratification as well as oxygen
depletion.
Bottom circulating
aerators are completely submerged and cause no break in the surface. They look
like large canons that pull water in at one end and push it out at the other.
This movement oxygenates the water horizontally.
Compressed air systems are
shore-mounted units that pump oxygen into the water through tubing. These have
the capability to cover large areas economically, while not disturbing the
natural aquatic landscape.
Choosing the right aerator
for the application is obviously critical. "For example, if a pond has a
severe algae problem, you need to look beyond aesthetics," says Bob Robinson,
fisheries biologist and director of sales and marketing for Kasko Marine in
Prescott, Wisconsin. "A fountain isn't the most efficient aerator for water
quality management. A lot of the energy they use is going into the spray
pattern instead of into efficient aeration."
Angela Hopko of Otterbine
Barebo in Emmaus, Pennsylvania agrees. "In general, the more decorative the
pattern, the less aeration they're producing." This doesn't mean that
consumers shouldn't choose display aerators in cases where water quality is an
issue. Instead, it means that they may need to add more units or use a
combination of systems.
Aerator placement is also
important. "If the pond is round it makes sense to aerate in the center," says
Hopko. "But if the pond is irregular or kidney shaped, you need to pay
attention to the danger areas. In a kidney shaped pond, if you put the aerator
in the middle, there will be dead zones. It would be better to place one unit
at each lobe."
Working closely with
manufacturers' specifications and your distributor will help you choose the
best system and work some of the bugs out before installation. "Get your local
distributor involved in the design process," says Hopko. "They can
troubleshoot things like electrical placement, pond depth, and other factors
that will help ensure success."
An aeration system is an
investment, sometimes a big one. But it can protect an even bigger investment
by ensuring a long and healthy life for the pond.
Source: Irrigation and
Green Magazine, April 2005, www.igin.com
