Pond And Aquarium Algae Removal: How To Get Rid Of Algae

Pond And Aquarium Algae Removal: How To Get Rid Of Algae

By: Jackie Carroll

One of the biggest problems faced by people who maintain aquatic environments is algae. Algae control for aquariums is quite different from methods used for garden ponds, but regardless of the environment, controlling algae depends on reducing the amount of sunlight and the level of nutrients in the water.

What is Algae?

You can think of algae as the microscopic weeds of aquatic environments. In the presence of strong sunlight and excess nutrients, algae builds up to form an unsightly growth on the surface of the water and on underwater plants, rocks and ornaments. It can also give the water a green, pea soup-like appearance.

Aquarium Algae Removal

The best algae control for aquariums is cleanliness. Use an algae scrubbing pad to remove algae from the sides of your aquarium. You can find algae scrubbers at any aquarium or pet supply store. Some are attached to long handles that make reaching the bottom of the glass easier. Beware of scrubbers attached to thin wooden dowels. Once saturated with water, thin wooden handles break easily when you apply pressure.

The best time to scrub off the algae is when you make a partial water change. Scrub the sides of the aquarium while the water level is low.

Algae also builds up on the substrate in the bottom of the aquarium. Remove the top layer of substrate and replace it with fresh material. Clean up the old substrate by laying it out in a thin layer to dry. When the algae dies, rinse the substrate and return it to the aquarium next time you clean it out.

If algae builds up quickly in your aquarium, make sure it isn’t sitting in direct sunlight.

Control of Algae in Ponds

Two factors that lead to an algae buildup in garden ponds are an excess of nutrients and strong sunlight. Fertilize the plants in the pond only when necessary, and use a slow-release fertilizer. Fish provide additional fertilizer in the form of droppings. Overfeeding fish results in an abundance of droppings and nutrient-rich water. Don’t overstock your water garden with fish and feed them responsibly to maintain a balance of nutrients in the pond.

Strong sunlight encourages the growth of algae. Surface plants, such as water lilies, shade the water. Consider covering as much as 50 percent of the surface of the water with water lilies. The fish will enjoy the shade and hiding places that the lilies provide, and they will also act as a biological filter to help keep the water clean.

A good rule of thumb for stocking your pond is to add six 4- to 6-inch fish and one large water lily for each square yard of water surface.

How to Get Rid of Algae with Herbicides

Using herbicides in the garden pond should be a last resort. Herbicides can kill your aquatic plants and harm the fish in your pond. If you absolutely need to use one, go with an EPA-approved herbicide developed specifically for use in garden ponds and follow the label instructions carefully.

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Read more about General Water Plant Care

Simple Care Guide

Unsightly algae blooms can hinder the natural beauty of your pond, and can become uncontrollable if left untreated. All ponds begin accumulating organic matter from the time they are first filled with water, generated by waste such as algae, dead plants, fish food and fish waste, and garden debris that may enter your pond, but API® pond products make it easy to control algae and other pond waste, so you can maintain clean and clear water to reduce maintenance over time. Spend more time enjoying your pond and less time troubleshooting!


Powerful and fast-acting POND ALGAEFIX™ algae control has been used successfully by pond owners for over 15 years to effectively control green water algae, string or hair algae, and blanketweed without harming fish or plants. Weekly use of POND ALGAEFIX algae control will reduce pond maintenance, and contribute to a clean, clear pond environment.

For those who prefer an alternative approach to algae control, MICROBIAL ALGAE CLEAN™ algae control contains patented, live bacteria to control green water and reduce organic sludge to promote a cleaner pond environment. It is the first bacterial algaecide to gain EPA registration, and may be used in ponds, fountains, and waterfalls with live plants and fish.

Getting Rid of Algae in the Freshwater Aquarium

The worst thing about running an aquarium is algae, and some fishkeepers even leave the hobby because of it. A clean, pristine prism of water can quickly become a green swamp, and once algae takes hold it is hard to get rid of. But don’t fret here are some tips on how to prevent or get rid of algae in the freshwater aquarium.

Lifegard Aquatics Nano Tank with Built-In Filter (8.3 Gallon) – CRYSTAL Elevated Low Iron Glass

Avoid Introducing It

This sounds obvious but avoid introducing any form of algae to your tank, as once it’s in there, it’s very hard to get rid of. Algae can be introduced on plants and can quickly transfer onto decor or into a mature filter, so only ever introduce plants that are free of algae, like tissue cultured. If it does find its way onto decor, the decor can be sterilized with bleach or dried out. If you have an old tank with a case of bad algae, don not transfer anything into the new one.

Scrape it Out

All tanks get algae, and the sparkling examples you see on Instagram are just cleaned more often or for the gram. Use a scraper on the inside glass daily to keep it algae free and prevent any build-up. An algae magnet to scrub algae while keeping your hands dry and if you do it little and often, just like any chores around the home, it prevents algae from growing into bigger, tougher jobs.

Siphon it Out

Just before the next water change, give the algae thorough scrape. Use a siphon to suck out all the dislodged algae spores and detritus that would go on to fertilize the next algae growth. Regular water changes are key to keeping algae in check, as it is physically being removed from the system each time.

Mag-Float Magnetic Algae Cleaner

Starve it Out

Algae thrive on spare nutrients that build up as byproducts in the water. Use nitrate and phosphate removers to soak up these algae fertilizers and remove them from the water. Algae uses ammonia too, so use a large biological filter to tightly cycle any ammonia as soon as the fish produce it. If your tap water contains fertilizers switch to reverse osmosis water for a purer source.

Naturally Graze it Out

Mother nature can help out with your algae battle in the form of algae-eating fish and invertebrates. Add a pleco, algae-eating loaches, even Mollies, and all will graze algae all day long, reaching all those little spots that you can’t. Small freshwater shrimp also work day and night to eat algae and polish every grain of gravel in the tank. They pay themselves off in free labor by helping you stay on top of it. Add an army of algae eaters of all kinds and you’ll notice the difference.

Deprive it of Light

A blackout can work as a last resort for bad algae manifestations as algae can survive many scenarios, but can’t live without light. Turn the lights off and completely cover the aquarium for two days. Plants and fish will be fine but algae can’t cope without this vital energy source. Lighting can be cut down to just six hours per day afterward which should weaken it enough to gain control of the algae.

Give it Some Competition

Live plants have been fighting algae for millions of years and can beat it in several ways. This time actually add nitrate, phosphate, and Potassium (NPK) to feed the plants so that they can grow is another method of how to get rid of freshwater algae. Rampant growth won’t let algae take hold and they can also overgrow it and shade it by covering the surface. They can emit natural algae fighting chemicals so give plants the right light, CO2, and fertilizer and they will fight algae for you, the natural way.

Kill it Off

In severe cases, algaecides can be used to get rid of algae in the freshwater aquarium, although they don’t address the root cause of the algae growth nor stop it from coming back in the future. They do, however, upset the equilibrium in the tank. Use algae treatments as directed but monitor the fish and make sure you add extra oxygen from an airstone. Remove any dead and dying algae from surfaces with a brush, and siphon it out and discard the water.

Zap it with UV

An ultraviolet sterilizer can be used to treat green water in an aquarium. Green water is tiny unicellular algae that float in the water and turns it into the color of pea soup. Connect a UV to your filter and algae that is exposed to the UV rays inside are damaged, causing them to clump together and die off.

Filter It Out

Algae thrive on nutrient sources. Slime algae, like Cyanobacteria, start in the least disturbed area of the tank where dirt collects and flow is low to non-existent. Use a powerful filter and/or powerheads to increase circulation all around the tank, lifting dirt and keeping it in suspension for the filter to remove. Strong water flow can help to tear sheets algae from rocks and gravel too. So trap as much fish dirt and particles from the water as you can with a powerful filter, just be sure to clean out the filtration often. A clean aquarium suffers much less from nuisance algae than a dirty one.

Use three in combination or even all of the above measures of how to get rid of algae in your freshwater aquarium for good. Cut down lighting, introduce algae eaters, scrape algae, change out more water, upgrade the filtration, and plant heavily and you’ll not only beat it, you’ll stop it from coming back.

How to Control Pond Algae

This article discusses the many factors involved in controlling algae growth in ponds. It is designed to better enable the pond keeper to have a full range of knowledge about combating algae growth.

Proper Equipment

Algae is one of the most talked about topics among new pond owners. Controlling algae is usually more of a problem for new ponds. A new pond does not have the proper balance of plants, animal life, and general biological function.

One of the most important things that you can do when setting up a new pond is to get the proper equipment installed. The pump you install should move at least 1/2 of the total pond volume for a water garden. The term “water garden” is assumed to be a pond with lots of plants and some fish. A koi pond usually has few plants and large fish requiring more filtration than a water garden. This type of pond is better off moving at least the full volume of the pond each hour. [ Pond Volume Calculator]

Besides moving the water you also want to filter the water. The pump should move water through a filter that is sized for your pond. See How to Select a Filter for a page that provides choices for several pond sizes and filter combinations for you. 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.

Proper Construction

Another major consideration for creating good water quality in the pond is one that is properly constructed. A pond 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. Thirty percent 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. A slight slope to the deepest level allows for easier removal of debris from the pond

A pond skimmer is highly recommended as it can remove up to 85% of debris before it sinks. The pond should be constructed so that rainwater does not flow over the yard and into the pond. This is one of the more common causes of algae in the pond. Rain runoff carries with it lots of organic debris that contain nutrients that feed the algae. Also fertilizer or chemicals could be carried into the pond causing problems. If your pond is already constructed you cannot do much about the depths of the pond but you can alter the area around the pond to make sure that runoff does not flow into it.

A pond built using concrete, limestone, or marble will also tend to have a high pH, which can contribute to greater algae growth.

Proper Maintenance

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. 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. The regular use of bacteria and enzyme products like Microbe Lift PL 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 which would otherwise promote algae growth. Learn more by reading our article on pond sludge

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.
[Pond Surface Area Calculator ]

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, as mentioned in the maintenance section above, 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 [ More information about UV sterilizers].

Filamentous algae have 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. Oxy Pond Cleaner can be very effective in cleaning up the rocks of the waterfall and stream.

We carry other products that will control algae during the time that your pond is maturing. Algaway is probably the most effective. Barley Straw and Barley Straw Extract can also be effective in improving water conditions for most ponds. Pond Dye shades the water, which limits the amount of sunlight feeding the algae. We carry blue and black dye , this is a cost-effective solution in large ponds and lakes, but it can be used in any pond. When treating for algae it is very important to ensure you have adequate aeration and do not exceed package directions.
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.

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.

Yet another means of algae control is a pond Ionizer. Ionizers can reduce algae growth by releasing a measured amount of minerals to the water.

Fluconazole Treatment

Fluconazole treatment acts as an algaecide that completely kills the excess algae in the tank. But, it is cumbersome to use and not a permanent solution. Relying on regular fluconazole treatments is an ineffective strategy as a complete fix to this problem. But, in certain scenarios, it can be very useful.

When your tank is plagued with a lot of bubble algae (or one of the other aggressive forms), you could try a fluconazole blast. It takes some time to work but kills the excess algae caked-on rocks, corals, and filters. After a fluconazole treatment, you should consider a full tank clean (within 8-10 weeks of the treatment) After this, introduce a few above-mentioned tank cleaner to help curtail the eventual re-emergence of algae in you beautiful tank setup.

Pond Algae and How to Control Algae

Algae forms in a pond when sunlight reacts with nutrients in the water. These nutrients are comprised of primarily Ammonia and Nitrate which you may recognize as the ingredients in fertilizer. These nutrients result from the breakdown of debris such as leaves, grass, and other windblown organic matter as well as from fish waste and uneaten fish food. As these items decompose, the nutrients become the food for algae in many forms including string algae that covers rocks and clings to the surface of your pond as well as the usual green water also called pea soup effect.

There are several ways to control your pond water and keep it crystal clear. Each have benefits and certain drawbacks and are detailed below.

  • A liquid or powder algaecide is the fastest way to clear up your pond but also the fastest way to kill your fish and pond plants. A liquid or dry algaecide will chemically destroy algae but is done so with harsh chemicals and compounds that are being increasingly monitored or banned by certain states and municipalities. With an algaecide, you can expect to see an overnight improvement but it comes at a price. The algaecide will be very hard on any plants you have in the pond. Additionally, the oxygen supply in the water will plummet. When algae are alive, they are living breathing plants that actually add oxygen to the pond water. Upon death, it rapidly consumes all the available oxygen in the pond.

If you intend to use an algaecide, please read the directions carefully as an overdose can quickly harm or kill your plants and fish. When using an algaecide, you will also want to increase circulation in your pond with a waterfall, fountain or aerator. These will replace lost oxygen and hopefully prevent a fish kill.

Finally, it should be noted that the dead algae will fall to the bottom of the pond and form the food for the next generation of algae.

  • A UV filter / UV Sterilizer is often used to clear up green water quickly in a pond. These items are both the same thing and differ only by how fast the water flows through them. A UV filter is a device that allows water to be pumped through it and bombards that water with Ultra Violet radiation from a bulb. The slower the water travels through the unit the longer the water stays in contact with the bulb and the more UV rays are absorbed. These UV rays sterilize the algae and it quickly dies. Use of a UV filter can clear green water in just a few days.

Unfortunately, UV filters only cover up the water quality problem. While they clear the green water, the underlying problem that caused it to begin with remains. Often the algae will come back in another form such as string algae which clings to the surface area of your rocks and pond liner. This algae does not pass through the UV filter so it is never treated and continues to thrive off the nutrients in the pond and the dead algae.

If you need to quickly clear the pond water, a UV is great but it should be used in conjunction with other treatments to eliminate the nutrients in the water and establish a natural balance in your pond.

  • Barley straw or liquid barley extract is a natural way to keep your pond clear. Barley straw bales have been used by farmers for hundreds of years as a type of natural algaecide but in reality it does not actually kill or remove the algae. Barley added to the pond will begin to degrade and break down. As the barley decomposes it releases enzymes that will slightly change the PH of the pond water. This change in PH provides the pond with a habitat that is less suitable to the growth of algae.

Use of the barley extract or barley bales is most effective before a pond has an algae problem. Both the bale and the liquid extract need to be retreated frequently so that the pond continues to have a new supply of degrading barely. Many people find this method very effective while others fail to achieve the results they hoped for. I believe this method is best used in conjunction with a pond bacteria product as part of a multi pronged approach to clear water.

  • Liquid or powdered pond bacteria is another popular way to establish a healthy naturally clear pond. Bacillus bacteria is found in all natural ponds and is part of natures way of keeping a healthy water cycle. Bacillus bacteria is a natural garbage disposal for your pond. As the colonies of bacillus bacteria grow, they feed on the very same nutrients that algae like to feed on. The bacillus bacteria will begin to consume decaying plant matter and fish waste and will continue to eat and multiply for 12-16 weeks. The regular use of a pond bacteria will ensure that continual new colonies of bacteria will emerge and scrub the pond clean of the nutrients that algae require to grow. If algae does not have a food supply then it cannot thrive.

Like the barley treatment, use of pond bacteria will require a bit of patience as the colonies take 2-6 weeks to grow and mature. This is a long term solution that should be considered as one of the best possible preventative measures to keeping a clean and healthy pond.

If you use a UV filter you will want to use the pond bacteria to help consume the dead algae and to reduce the nutrients in the water.
If you use a chemical algaecide, you would want to follow with a large dose of pond bacteria to consume the dead algae before the next cycle begins.
If you use a barley extract, you will want to consider adding the pond bacteria to reduce the nutrients that feed the algae.
If you use a debris scrub on the surface areas of your pond then follow with treatments of bacteria to your pond.

The bacteria will attach itself to any surface area in the pond and is invisible. However, if you add bio media such as bio balls into the waterfall filter of your pond, that media will house large colonies of beneficial bacteria and will scrub the water as it passes over.

Pond bacteria comes in both liquid and powder and each method has its own following. The powered form is generally more potent and treats a larger area but the liquid is easier to apply. Look for a high concentration of bacteria colony forming units (1-5 billion) when making your purchase. These CFU numbers will tell you how potent the product is. Unlike an algaecide, you can double treat and dose frequently with bacteria without any worry of over treatment or harm to your plants and fish from this naturally occurring bacteria

Special winter note: During the falls leaves and other debris will accumulate on the bottom of your pond. Use a winter blend bacteria or a super concentrate and treat through the winter. The bacteria will continue to consume debris through the winter and will allow your spring startup to be more problem free.

  • Other algae reducing tips will help control algae in your pond and will help make any of the above treatments more effective.
    1. If possible, plan your pond so it is not in the direct sunlight the entire day. The cooler the pond the less problem summer algae will be
    2. Add water plants to your pond up to 30-40% of the surface area of the pond. These plants will both reduce the temperature of the pond and they feed off of the ammonia and nitrates in the water
    3. Do not over feed your fish. Goldfish and Koi typically do not require daily feeding. Some customers tell us that they feed their fish 2-3 times a day. The more fish waste the more nutrients in the pond for algae to consume. Feeding fish should be done no more than once a day and they should be given no more food than they can consume in 2-3 minutes. In a pond with full algae bloom, I would not feed the fish at all until it is under control. The fish will be happy eating the algae itself and it is probably better for them that the regular fish food.
      NOTE: Once the temp of the pond water falls below 50 degrees do not feed the fish at all as their system cannot properly digest it and you can harm or kill the fish.
    4. Do not overstock your pond with fish. A general rule of thumb is 1 inch of fish per 100 gallons of water in your pond. That is probably a very conservative estimate but if you have a 400 gallon pond stocked with 20-30 goldfish or koi that are 1-3 inches long, you are going to require a considerable amount of filtration and treatments to handle that kind of fish load.

Final note: Pond maintenance should be a simple quick routine done on a weekly or bi-weekly basis. The use of the proper items to care for your pond will ensure a safe and happy home for your pond plants and fish and will give you more time to enjoy your pond instead of working on it.

Graystone Industries and its web sites offer many pond water care items which may be viewed at www.graystonecreations.com. At this time, we do not offer any chemical algaecide products as we firmly believe that the harm to the fish and plants in the pond outweigh the benefit of killing the algae. We do carry UV lights, bacteria, barley extract and other effective and safe pond water treatments.

Written by: John Olson CEO of GraystoneCreations.com

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Watch the video: Best Way to Remove Algae from your Pond