Pond Algae Control & Maintenance
Drs. Foster & Smith Educational Staff

Pond algae control & maintenance Pond algae control & maintenance
Many pond owners assume that the presence of any algae in their pond is a cause for concern. While it is true that algae can easily turn an attractive pond into pea soup, it also has many benefits.

For example, algae helps your pond appear more natural and provides fish with a healthy food and oxygen source. Thus, your goal should not be to eliminate all algae. Instead, it should be to manage its growth to keep the population at a desirable level. Knowing what factors contribute to algae growth, and your control options, will help you keep a healthy, well-balanced pond.

Growth factors affecting algae
Unless you live in one of the southernmost portions of the U.S., your pond experienced big changes over the past winter. With your plants removed or dormant, fewer nutrients were absorbed from the water. Organic matter collected in the bottom. The water quality declined. It lost oxygen and much of the valuable, natural bacteria it needs to control ammonia and nitrite. As a result, pumps and filters became less efficient.

 
Your first control step:

test to determine what the algae is feeding on

To control algae you need to understand the chemistry of your pond, and then take corrective measures. We recommend that you use a quality test kit to regularly check the levels of elements such as nitrite, nitrate, and phosphate, and a thermometer to track water temperature.

If nitrite or phosphate are present, or nitrate levels are high, you have several control options. Depending upon conditions, all are effective. Sometimes a combination of options works best.

But as the days lengthen this spring, the "open" water in your pond, not yet shaded by nearby trees or the leaves of in-pond plants, is receiving a dramatic increase in sunshine. Conditions are now perfect... for algae growth.

It is important to understand that it is normal for most ponds to experience a "spring bloom" of algae. Pond owners should not be overly concerned, because, in most cases, the pond, and your regular seasonal management practices, will balance itself in four to six weeks. The amount of algae will diminish, and the water will clear.

As you reposition plants to their shelves, or add new plants, they will begin to utilize nutrients, and, at the same time, their growing leaves will shade the surface of the water. As you clean your filters and pumps, they will be restored to normal efficiency. Ammonia and nitrite will be reduced as your bio-filter re-populates with bacteria or you can give it a boost with a biological conditioner. And the water will be oxygen enriched as you reconnect waterfalls or other effects. As a result, you should see a reduction in algae.

If algae is persistent, or appears later in the year, it is usually a symptom of an imbalance in the pond. The most common reason for any algae bloom is an excess of nutrients, but these are not at work alone. Additional factors such as extended sunlight, warm water temperature, and high phosphate and CO2 levels are likely working together to accelerate algae growth. These problems are not as difficult to solve as many pond owners think.

 
Help combat algae with the following:
AlgaeFix  
Frothy Pond Fountain
Aerating Pond Pumps
 
AlgaeFix  
Water lilies planted in a koi pond.
Plant water lilies to provide shade.

Control options
Additives
A number of liquid, dry granulated, and shade products are available to control algae. A good choice is AlgaeFix because it is easy to use and provides effective, selective control of algae, while not harming fish and ornamental pond plants.

When it comes to additives, too much of a good thing can produce bad results. For example, killing algae too fast can quickly deplete the oxygen supply in your pond. Oxygen levels can also be quickly reduced by warm weather at this time. As a result, fish may die.

It is important to use additive products at labeled rates. If they do not work fast enough to satisfy your needs, you should add filtration or do a water change rather than increase dosages.

Filtration
A UV sterilizer, installed in your pond, is a safe, effective, and proven way to remove floating algae. A properly performing UV sterilizer can achieve a 99% reduction in waterborne algae. In addition, the cleansing effect of UV sterilization may eliminate many harmful biological organisms.

UV sterilization by itself will not adversely affect your pond's inhabitants, requires little maintenance, and is available in various wattages, so it is easy to match to any pond size. Adequate biological and mechanical filtration must be used when operating a UV sterilizer, as the added waste from the dying algae must be removed regularly to avoid toxic water conditions. It is important to clean all mechanical and chemical filters regularly, and even more frequently when using additives to control algae.

It is important to recognize that UV sterilization could also kill any beneficial bacteria free-floating in the pond. While this is not a problem in an established system, it may be necessary to delay use of the unit to allow for re-growth of bacteria after your filter has recovered from the winter. Use of bacterial additives is not recommended in ponds while running a UV sterilizer because the bacteria will likely be efficiently eradicated.

Barley Straw Pellets
Natural barley in many forms - mats, pads, pellets, sticks, bagged straw, and even liquid extract - releases soluble carbohydrates that cause algae to clump together and sink. The mats also provide both biological and mechanical filtration, and, to keep your pond attractive, can be cut to fit in virtually any filtration system where they will be out of sight.
Phosphate originates from many sources. It is present in the food you feed your fish. It is often added to tap water by municipalities. And, it can come from fertilizers in run-off water. If your test indicates high levels of phosphate, placing PhosGuard in your filter, for example, will help filter out both organic and inorganic phosphate.
Aeration
Algae thrives in poorly oxygenated water. Your pond will get an immediate boost if you install a waterfall, fountain, or aerator to agitate the pond surface and help release gases such as CO2. This also enables the water to absorb more oxygen, which will, in short time, help reduce the presence of algae.
Water Change
If your water test indicates high nitrate or an excessive level of organic matter, do a partial water change. The first steps are to remove any debris in the bottom of your pond, and then clean your pond filter and pump thoroughly. Next, remove and replace approximately one-third of the water. During this step be sure to add a dechlorinator if your water source contains chlorine. To minimize the amount of organic matter in the water, do not add any new fish to your pond while it has excess algae, and feed your fish only what they can consume in a couple of minutes.
Shade
If your pond gets too much sun, create shade. If space is available, you can add plants like water lilies and water hyacinths. These will provide instant shade, help cool the water, and will absorb nutrients. If there is limited space in the pond, consider erecting an arbor or adding harmless blue or black dyes to block or filter the sun.

Most algae problems can be controlled with the right treatment, especially if diagnosed early. Don't put off testing or corrective action.

  
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