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Water Treatments: Controlling Algae  September 24, 2007

Controlling algae is an important issue for new pond owners and caretakers. New ponds especially do not always have the proper balance of plants and animal life. First it is necessary that the pond or lake is properly constructed. It should have about 40% of its surface area for the deep zone, which should be at least two feet for a water garden and three feet or more for a koi pond. 30% should be an intermediate depth of 1-1/2 to 2 feet and the remaining 30% at least 1 to 1-1/2 feet deep.

Here is some information on additional water features that will keep your water clear and glistening, and not looking like a misbegotten fishtank.

Proper Equipment

One of the most important things that you can do when setting up a new pond or maintaining a pond is to ensure that proper equipment is installed. The pump you install should move at least 1/2 of the total pond volume per hour for a water garden, which is a pond with a high amount of plants and some fish. A koi pond usually has few plants and large fish, requiring even more filtration than a water garden. This type of pond is better off moving at least the full volume of the pond each hour. Larger ponds and lakes should be ideally turned over every three to 30 hours, depending on the size. On the other hand, certain plant life like water lilies prefer water that is more still.

There are many pumps available on the market that feature remote control, lighting, and timers such as Aquamaster and Aqua Control, Otterbine Barrebo, Kasco Marine, and Lake Fountains.

In addition to moving the water you also want to filter the water. The pump should move water through a filter that is sized for your pond. Biological filtration takes several weeks or months to mature to the point that it makes a major improvement on your water quality. The filter needs to run 24 hours a day 7 days a week to work. The filter is one of the first things to check if algae starts to develop.

Proper Maintenance

The regular use of bacteria and enzyme products like AquaPros by Pifer, Natural Environmental Service’s Pondkeeper, Savio’s line of products, EcoFix, PondZyme Plus, the Ecological Laboratories line of products, GreenEx, or Simply Clear is not only good for the overall pond water quality they also help reduce odors, improve the health of the fish, reduces the amount of sludge in the pond, and reduces algae.

If algae becomes prominent consider algaecides like GreenCleanPro by BioSafe Systems, GreenEx or Winston’s CrystalClear® Algae-Off®. Some debris buildup in the pond bottom is normal. As long as this sludge is no more than 1/4 inch or so, physical removal is not necessary. In a properly constructed pond this debris ends up in a fairly small area where it can be removed when necessary. Consider Misty Mountain’s Sludge Away. Course material like string algae and dead leaves can be removed with a net. A skimmer net or algae net does a good job of this. If the debris is too fine to be removed with a net then a pond vacuum works well. Using the following products should reduce the sludge and keep it to a minimum.

Proper Plant Balance

If you have a water garden and not a koi pond then make sure you have the right types and numbers of plants in the pond. Anacharis or other underwater plants and floating plants remove excess nutrients from the pond by absorbing these nutrients for their own growth and starving the algae for its food source. Also provide approximately 2/3 surface coverage using water lilies, floaters (like Water Lettuce or Water Hyacinth), or other plants that shade the surface of the water. These plants reduce the amount of sunlight that penetrates the pond; this helps keep the water cooler and starves the algae for sunlight.

Even though you have set up your pond using the right components, have added the proper type and number of plants, and do not have an excessive number of fish you could still have some algae. This is especially true when a pond is young. Other methods of algae control may be called for during the first few years of a pond. As a pond matures (as long as it hasn’t been totally emptied and refilled) the algae gets less and less and may no longer be a problem.

Additional Algae Control Methods

What can we do while we are waiting for our ponds to mature? One thing that every pond owner should do is to add beneficial bacteria and enzyme products to their pond on a regular basis. Not only is this good for the overall pond quality it reduces odors, improves the health of the fish, reduces the amount of sludge in the pond, and reduces the algae. If your problem is green water then you can solve this easily by installing an ultraviolet sterilizer. This is the only way to guarantee clear water 100% of the time. Another method that is very effective for algae control is the ECO-Aqualizer. This device also helps the bio-filter operate more efficiently.

Barley extract for pond and water garden algae control is a natural solution for maturing ponds, although it is also effective for most ponds and lakes.
Another newer technology involves ultrasonic waves that disrupt the cellular function of algae. One type of this equipment is SonicSolutions® which floats below the surface and kills algae by producing a precise frequency of ultrasonic waves. It is supposed to be safe for all other fish, plants, and other aquatic life, and it can even help lower pH and TSS.

Pond Dye shades the water, which limits the amount of sunlight feeding the algae. Blue and black dye is a cost-effective solution in large ponds and lakes, but it can be used in any pond. If your pond does not contain fish then Fountec is a great product to use. This product is safe for pets that may drink from the pond but not for fish. Or, in ponds without plants Pond Block is a good option.

A Final Note

Filamentous algae has many algae cells attached together. It comes in many forms, it can be long and stringy, it can be short and furry or in the shape of webs or mats. The short velvet type of algae that covers the liner and everything else in the pond is beneficial. It helps provide a natural appearance to the pond. It uses nutrients from the water, provides oxygen during the day, and the fish nibble on it. This type of algae cannot be totally eliminated with fish and plants in the pond. String algae, which may coat the waterfall, is a little harder to control. You can physically remove it from the pond where possible. Filamentous type algae will flourish on waterfalls and in shallow streams because the sunlight is more intense providing more heat and light than what may be in other parts of the pond and there is a constant supply of nutrients flowing through it.

Remember that fish and fish food add nutrients to the pond, which in turn feed algae. Don’t add more fish than your pond and filter will support and don’t overfeed your fish.

To Summarize:

Keep the organic load down by keeping runoff out of the pond and the sludge to a minimum. Vacuum sludge that has already accumulated. Less than 1/4 of an inch of sludge on the bottom should not be a problem.
Don’t over feed or keep more fish than your pond will support.
Install a large biological filter and give it time to work; this could take several months.
Use enough, and the right type of, aquatic plants. This means surface plants for shade and floaters and underwater plants to remove excess nutrients.
Use biological treatments and give them time to work. This is an ongoing process and takes time along with the methods outlined above for balancing your pond.
Use an algaecide to eliminate existing problems more quickly.
Install an ultraviolet sterilizer for the most effective control of singe-cell (green water) algae.

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