Ecological Controls for Healthy Ponds

By Ronald Pifer

B.S. Mechanical Engineering, DukeUniversity

M.A. Environmental Biology, Univ. of Colorado

Society of Sigma Xi, Scientific Honor Society

 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 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, where poisons are introduced.  A new term was even coined to characterize this phenomenon, biological magnification, and since that time, children all over the country have been taught this concept in their ecology units and lessons. As a result, a new understanding and beginning seemed to be on the horizon.

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 are 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 Bagic 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 process 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 tn 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, are 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 45 years in Ecological Consulting; including 7 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 20 years in the Bacterial Products Industry. He may be reached at: Environmental Solutions, P.O. Box 714, Stevensville, MT 59870, U.S.A.; or thru the web at www.environmentalsolutions.net or by email at environment@hushmail.com; or by phone at 406-777-4990.