ECOLOGICAL
CONTROLS FOR HEALTHY PONDS
By Ronald Pifer
B.S. Mechanical Engineering, Duke University
M.A. Environmental Biology, Univ. of Colorado
Once when I was a young boy, standing on a beach in Florida, I looked skyward and noticed a low flying plane, dropping what looked like water out of it's bomb bay doors. "What's that," I asked. "Why that's DDT, Ronnie, and it's going to kill those pesky mosquitoes that are always trying to carry you away and eat you up!" Well, what a relief, I thought, isn't life great!?
Now I am much older, and more experienced, and as Paul Harvey so aptly reports,
I have learned the rest of the story! That story was first chronicled for me in
Rachel Carson's classic book, Silent Spring, where she laid out a pattern of
insidious poison concentration that occurs in the food chains. A new term was
even coined to characterize this phenomenon, called biological magnification.
Since that time, children all over the country have been taught this concept in
their ecology units and lessons, and a new consciousness has been created.
Unfortunately, real life considerations have their practical side, and poisons
are still used and embraced by most of us working in the turf, landscaping, and
farming industries. Fortunately, alternatives have always existed, and they are
increasingly being implemented and employed in all of these industries. In these
cases, the result is a more stable and healthy environment, which is more
capable of sustaining negative and potentially harmful hits from the weather,
pests, and toxins from external sources. The bottom line can also be lower
operating costs and more money in the pocket!
The Basic Ecological Approach to Pond Management. I was recently asked by one of
the most esteemed, environmentally-oriented superintendents in the golf course
industry to state the main components of ecological pond management. Here is
what I told him:
1) Restrict or Reduce the Source of Nutrients Entering your Pond(s). This
objective can be accomplished by: (a) reducing the use of fertilizer around the
border of your pond; (b) by placing slight drainage depressions around the pond
to divert the nutrient-rich runoff from entering the pond; (c) by placing
impermeable catchment basins in strategic locations to catch, divert, and
possibly evaporate the incoming water; and (d) by placing a border of native
wetland vegetation along the edge of the pond, to absorb the incoming nutrients
and to provide an attractive border.
2) Employ Biological Controls to Keep the Pond(s) in Ecological Balance and
Maintain its Long-Term Health. This objective is designed to help the pond
manager offset the nutrient loading to the pond environment, which causes algae
blooms and can cause bad odors, fish kills, and unsightly appearances. There are
two main approaches to accomplishing this objective and they can be used in
combination with each other. The first one, and the most basic is to introduce
high concentrations of pond bacteria and enzymes, to act as "packmen"
and eat up the nutrient-rich film on the submerged surfaces. This attacks the
problem at its source and keeps the pond in proper ecological balance. The
second approach is to introduce plant-eating fish to consume the results of
those high-nutrient concentrations: the dreaded algae, pond scum, and aquatic
weeds. This approach is legal is some states, while illegal in others. However,
it can be somewhat effective when the stocking rate is optimal and the
biological conditions are proper. In both cases, the beneficial results are
gradual, when compared to using poisons, but the long-term health of the pond is
far superior to the "kill 'em with poisons" approach.
3) Use Mechanical Measures to Maintain High Oxygen Level. This approach is often
used to support the pond bacteria in digesting the nutrient input and
controlling the algae blooms and aquatic weed problems. It can and should be
used in conjunction with the previous strategy, since it enhances the health,
vitality, and productivity of both the beneficial bacteria and the plant-eating
fish. It can be accomplished by a variety of devices, including propeller-driven
fountains, normal air blowers and diffusers, or the more expensive ozonators and
diffusers. Furthermore, some pond managers create beautiful waterfalls that
accomplish a similar objective in an aesthetically pleasing manner.
4) Use Sun Screens or Tinting Dyes. This approach is often useful for
restricting incoming light to the photosynthetic process of the algae. It is
most economically feasible in smaller ponds that are not used for pumping or do
not have excessive turnover or water loss. However, it could only be considered
part of the ecological approach if the product itself is easily biodegradable by
natural or introduced pond bacteria.
5) Physically Remove and Dispose of Any Remaining Algae. As you might expect, a
properly managed pond system will clean itself, yet the removal of nutrients may
also produce some dead or dying algae. Some of this biomass will sink to the
bottom for future decomposition, while some will float on the water surface. The
dead, floating algae can be removed by physical means, if so desired. However,
if this is done, the algae mass should be taken to a location outside of the
immediate pond drainage area, so that future decomposition does not provide a
source of additional nutrients for the pond.
The Basic Poisonous Approach to Pond Management. The normal approach to managing
ponds is to use algaecides, which are usually copper-based poisons that are
approved and regulated by government agencies. These chemical strategies often
provide a "quick fix" if applied properly, but they can also result in
fish deaths if applied too heavily. More importantly, this approach introduces a
toxin into an aquatic ecosystem that also kills or inhibits the pond's
beneficial bacteria and also will become incorporated in the aquatic food chain.
This consequence becomes important when you consider that some or most of the
algae being killed by the algaecide are sinking to the pond's bottom, where they
enter the pond's decay cycle. Here, the small aquatic organisms and the
beneficial bacteria normally break them down and return the nutrients to the
water for more algae growth. However, continual use of algaecides inhibits the
pond's ability to properly digest and dispose of these periodic discharges of
"algae carcasses."
This condition results in a bottom layer of organic slime and sediment that
becomes a partial dead zone, where anaerobic and facultative aerobic bacteria
work very slowly in a low-or-no oxygen environment. It also is a zone that is
favorable for pathogens, including E. Coli, and other organisms that are harmful
to both aquatic life and humans. Furthermore, the by-products of the bacteria
are often hydrogen sulfide, which smells like rotten eggs, and/or methane gas.
There may also be a "dead fish" smell that accompanies this stage in
the pond's sick state of existence.
At this point Superintendents are often told by consultants that they need to
install expensive aeration systems, in order to deal with the odor problem. This
approach should help the odor problem, as well as some of the decay processes in
the pond's bottom. Unfortunately, the pond is still out of ecological balance,
and over time will require heavier and more frequent doses of algaecides to
maintain proper weed control. This consequence will require additional funding
from maintenance budgets and will keep the pond headed towards further
eutrophication, or the accumulation of nutrients, and more serious algae
problems...
The Bacterial Approach to Pond Management, Normal pond bacteria are useful for
recycling nutrients and keeping the pond in proper ecological balance. However,
these bacteria do not necessarily dispose of the nutrients that are a key
component of algae blooms. Therefore, when a net gain of nutrients is occurring
in a pond environment, it becomes necessary to supplement the native bacteria
with special formulations that emphasis nutrient disposal versus nutrient
recycling. Some of these introduced bacteria break down carbohydrates, proteins,
and fats into their main components. Others break them down further, until the
end products are carbon dioxide and water.
Yet, the most important part of any nutrient disposal formulation is the
addition of those types of bacteria that dispose of the primary nutrients for
algae blooms: nitrates and phosphates. Most importantly, though, the better
formulas should contain de-nitrifying bacteria, which convert nitrate into
nitrogen gas, and those bacteria that bind up the phosphates. The resultant mix
of introduced bacteria can then convert the nutrients in the organic film into
carbon dioxide gas, nitrogen gas, and water. In order to accomplish this kind of
result, a beneficial bacterial formula must contain multiple bacteria species.
For example, our product, AquaPros, contains 11 species of bacteria and 7
different enzymes. Most of them perform multiple functions, yet, when taken in
total, they cover the full spectrum of decomposition activities that are
required in this type of management strategy. This is the kind of total and
complete formula that is needed for a successful program.
Other components for a successful Bacterial Program are: (1) the biological
conditions, existing in the pond. (2) the concentration, or cells/gallon, of the
bacterial formulation: (3) the viability of the bacteria: and (4) an effective
means of dispersal into the pond(s)). The conditions in the pond are best when
there exists adequate aeration, or water movement (which may be mechanical or
natural); when the temperature is between 60P and 90F; and when the pH is
between 6.0 and 9.0. Ponds that are stagnant, or have little natural or
artificial water movement, may require heavier or more frequent pond treatments.
Most bacterial products are sold in the powder form, being freeze-dried and
containing start-up, growth nutrients, while other bacteria are sold
semi-dormant, in the liquid form. The bacterial concentration varies according
to the product being sold. For example, the liquid formulations may have 100
billion or more cells per gallon, while the powder formulations may have from
several billion to 10 billion cells per gram. This latter type can result in
about 1/2-to-l trillion cells per gallon, for one pound of product. Furthermore,
one formulation that we market, called Super AquaPros, may be "brewed"
up to ultra high concentrations, exceeding 15 trillion, or 1,500 billion, cells
per gallon. This formulation was designed to reduce shipping costs, when
servicing clients in the Orient.
From the standpoint of dispersion, the least productive approach may be the
bacteria that are sold in bio-disposable bags. They are designed to be placed on
the pond's surface, to be blown around by the wind and to slowly disperse into
the water column. The next level of treatment is to disperse the product by
hand, throwing it into the pond, waiting around the entire pond at the water's
edge. If the product is already liquid, it is ready to go; if it is in the
powder form, it needs to be brewed in non-chlorinated and non-toxic water and
then dispersed. Of course, the best means of dispersal may be a water pump, if
the pond is big enough, or at a headgate, if major volumes of water are flowing
into the pond.
Once you try a bacterial product, make sure that you use enough product to
achieve noticeable results. This may require you to use 1.5X-to-2.0X the
maintenance dosage the first time, in order to kick off the process. Also, make
sure to carefully follow the brewing instructions, if there are any, and
disperse the product in the most effective manner possible.
Evidence of a successful treatment is apparent in several different ways: (l)
Within a week the bacteria should have started to clean up the organic film,
located along the edge of the pond. This action creates a kind of "vacuum
cleaning effect! (2) Within a week, any odors should have disappeared, as the
beneficial bacteria start to out-compete the resident bacteria for nutrients and
reduce the hydrogen sulfide production. (3) Within a week, the green or
blue-green color of the water should be reduced and the water clarity should
improve. (4) After several weeks the algae surface scum and some of the rooted
aquatics may start to turn yellow, then brown, as the nutrients are removed and
their health deteriorates.
Fishery Management Options. Fishery options can be a favorable component of a
well-managed ecological program. They should be chosen, according to your legal
and financial constraints, as well as the type of plants that you expect them to
consume. In general, there are two main types of aquatic plants in a freshwater
pond: (1) the phytoplankton, or single-celled, suspended algae, which give the
water a green or blue-green color, and (2) the rooted aquatic plants, or weeds,
which grow from the bottom upwards. They include the normal leafy plants, as
well as the pond scum.
To remove the first type of plant, the phytoplankton, the Israeli Carp or the
Tulip is a possible choice. I am most familiar with the Tilapia, since my former
company. Solar Aquafarms, is the largest Tilapia farm in North America. This
fish is a superior filter feeder and can live almost exclusively on the tiny
algae that they filter from the water. Solar Aquafarms uses this characteristic
to recycle the fish waste into algae ponds, which are, in turn, pumped back to
the fish, to supplement their diet!
The other popular algae eater is the grass carp, which is sometimes called the
White Amur. It is popular due to its heavy appetite for some types of rooted
aquatic vegetation and due to the fact that is produced with three sets of
chromosomes, instead of two, and is sterile. However, it does not eat all types
of algae and it often creates turbidity problems, due to its heavy activity in
the shallow areas along the pond's borders. And as many of you know, it is also
illegal in many states due to the concern of illegal releases and potential harm
to the preferred game fish.
Suggestions for Long-Term Success. Superintendents, who have not tried all of
the ecological strategies that are available to them, should consider the
choices listed in this article. The two most important of these strategies are:
(1) to minimize the source of the nutrients flowing into the pond and (2) to
reduce the nutrients that make it to the pond. The first strategy is
accomplished by drainage design, vegetative patterns, and fertilizing patterns,
while the second strategy is accomplished by a well-designed, bacterial
treatment program. In both cases, you are attacking the algae at its source - by
removing its life-giving, vital nutrients. Naturally, these ecological
strategies are enhanced with good water movement or aeration; organic sun
screens, when desirable and appropriate; the addition of algae-eating fish, such
as the grass carp, when you can use them; and the periodic removal and remote
disposal of dead algae when it appears.
Most of the strategies are already familiar to most of you, with the exception
of the bacterial strategy. I hope I have given you a better understanding of how
it works and how it can benefit you. If you haven't tried it, I suggest that you
do. It might even be fun for you to see your pond go through the improvement
phases that normally accompany such an approach. If you have any questions,
please call or e-mail me, and I will be happy to answer them and assist you in
any way I can.
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Mr. Pifer has spent over 35 years in Ecological Consulting; including 5 years in Aquaculture R & D; 15 years in environmental impact assessments; 15 years teaching science at the junior high, high school, and college levels; and over 10 years in the Bacterial Products Industry. He may be reached at Pifer Environmental Services, 791 Rabbit Run, Stevensville, MT 59870, U.S.A.; or www.environmentalsolutions.net; or environment@accessmtwildblue.com; or toll-free @ 800-706-4990, or direct line @ 406-777-4990.