Sick of Pond Slime? How to Get Rid of Algae for Good

Sick of Pond Slime? How to Get Rid of Algae for Good

If you've got a large pond on your property, chances are you're familiar with that slimy, smelly green gunk that seems to take over every summer - algae. It's not just unsightly and foul-smelling, but out-of-control algae can wreak havoc on your pond's ecosystem, too.

Whether it's thick mats of green slime covering the surface, murky green water you can't see through, or stringy globs wrapping around everything, algae blooms are the bane of every pond owner's existence. 

The good news? You don't have to just accept that gross algae invasion every year. With some know-how and careful pond maintenance, you can get rid of existing algae and prevent it from coming back.

In this guide, we'll cover all the most effective strategies for controlling algae in large ponds without resorting to harsh chemicals. From low-impact natural methods to handy removal tricks, you'll be armed with plenty of ways to win your battle against algae once and for all.

Why Do I Have Algae In My Pond?

There are a few reasons why your once-peaceful pond might have turned into a slimy green mess. Algae are microscopic plants that thrive in warm, nutrient-rich water. So, if your pond has excess nutrients from decaying plant matter or animal waste, you're basically inviting algae to move in and take over.

In a way, you’re still succeeding at creating a thriving ecosystem – just not the one you wanted when you first built your pond! Fortunately, there are plenty of ways to regain control and restore balance to your pond.


One potential culprit for excess nutrients is overfeeding fish or other animals in the pond. When there's too much food available, it can lead to an overgrowth of algae as well as other unwanted organisms. So, make sure you're not overfeeding, and consider adding more plants to help absorb some of those extra nutrients.

Too Much Sunlight

Another common factor is too much direct sunlight. Algae love warm water, and sunlight provides the perfect conditions for them to grow rapidly. Consider adding shade-producing plants or installing a fountain or waterfall to provide some shade for your pond.

An Overabundance of Sediment

If your pond has a lot of sediment at the bottom, this could also be contributing to excess nutrients. The sediment can contain decaying organic matter, which releases nutrients into the water. 

Regularly cleaning and removing excess sediment can help reduce nutrient levels in your pond. Additionally, adding beneficial bacteria to the bottom of your pond can also aid in breaking down and reducing excess sediment.

Natural Algae Control Methods

The most effective and eco-friendly way to get rid of algae is to start with some natural, low-impact control methods. These allow you to regain a balanced pond ecosystem without harsh chemicals.

Use Barley Straw

One surprisingly simple trick is adding barley straw to your pond. As the straw decomposes, it releases hydrogen peroxide, which helps control algae growth. 

Just anchor a few bales or netting bags filled with barley straw into your pond. The slow, steady release of hydrogen peroxide is enough to inhibit new algae without harming plants, fish, or other pond life.

Introduce Beneficial Bacteria

Beneficial bacteria like those found in eco-friendly water treatment products can outcompete algae for nutrients. As the good bacteria multiply, they'll consume the excess nutrients that were feeding algae growth. Look for pond-safe bacteria blends and follow instructions for proper application.

Plant More Aquatic Vegetation

Aquatic plants like water lilies, lotus, and pond weeds don't just look beautiful - they also help starve algae of nutrients and light. Aim to have around 60% of your pond's surface area covered with vegetation to limit the areas where algae can take hold. The plants will absorb nutrients while providing shade that restricts algae's access to sunlight.

Aeration is Key

Ensuring proper water circulation and aeration is another way to make your pond less hospitable for algae. Install a pond aerator or fountain to increase oxygen levels and keep water moving, both of which help inhibit algae blooms. Increased aeration also allows beneficial bacteria to better outcompete algae.

Stock Up on Algae Eaters

For an extra level of natural algae control, consider adding some algae-eating fish, invertebrates, or aquatic animals to your pond's ecosystem. Grass carp, Koi, and Goldfish all enjoy munching on stringy or mat-forming algae. Small invertebrates like snails can also help control algae growth.

Mechanical Algae Removal Methods

While natural methods are best for long-term algae control, sometimes you need a more hands-on approach to quickly clear up existing blooms. These mechanical removal tactics can help you physically remove algae from your pond.

Use a Rake or Skimmer

For minor algae accumulations on the surface, a simple rake or skimmer net can do the trick. Gently rake or skim off any visible algae clumps, mats, or scum off the top of the pond. This works best when you catch algae blooms early before they become too widespread.

Install a Pond Vacuum

For denser, bottom-growing algae, a pond vacuum can be incredibly effective. These underwater vacuum cleaners suck up algae, debris, and excess nutrients from the pond floor and get them out of the water. Regularly vacuuming will help reduce the nutrients that feed algae growth.

Try a Tarp or Shade Cover

You can temporarily cover all or part of your pond with an opaque tarp or shade cloth. This blocks sunlight from reaching the water, depriving algae of the light it needs for photosynthesis. Let the tarp cover about 60-90% of the pond surface for several weeks to starve out algae.

Chemical Algae Treatments

In extreme cases, you may need to turn to an EPA-approved algaecide or herbicide formulated for ponds and lakes. Copper sulfate compounds are commonly used to kill existing algae.

However, algaecides can be hazardous to use around humans, pets, or wildlife when not applied properly. They can also harm beneficial plants and organisms, so use them minimally and carefully follow all instruction labels.

Aeration Systems - Your Secret Weapon Against Algae

While methods like bacteria, plants, and skimming can go a long way, one of the most powerful algae-fighting tools is a properly designed aeration system

Aeration does double duty to make your pond extremely inhospitable for algae. Not only does it add oxygen to the water, but it also circulates the water, preventing stagnant areas where algae can thrive.

Plus, proper aeration promotes beneficial bacteria growth, which helps to break down organic matter that feeds algae. By keeping the water moving and improving its overall health, aeration can greatly reduce the likelihood of an algae bloom.

Are you looking for a quality pond aeration solution that will effectively fight algae and keep your pond healthy? At Living Water Aeration, we can help you with our line of top-rated aerators and other pond maintenance products.

Don't fight algae blooms year after year. Trust Living Water Aeration's expertise to design and install the powerful aeration system that will starve out algae and keep your large pond healthy and algae-free for years to come.

See Our Aeration Lineup


Does vinegar kill algae in ponds? 

Yes, vinegar's acidity can kill algae when applied directly. However, it may take several treatments, and vinegar can harm other pond life, so it's not an ideal long-term solution.

How do I get rid of algae in my pond without killing fish? 

Focus on natural, eco-friendly methods, such as adding aerators, barley straw, beneficial bacteria, and plenty of aquatic plants. Avoid harsh chemical algaecides.

What is a natural algae killer for ponds? 

Some of the most effective natural algae killers include hydrogen peroxide, barley straw extracts, and introducing algae-eating fish like grass carp. Proper aeration and circulation are also key.

Why is there so much algae in my pond? 

Excessive algae growth is typically caused by too many nutrients in the water, such as uneaten fish food, decaying plant matter, fertilizer runoff, or lack of aeration.

Will algae go away on its own in my pond? 

While algae levels fluctuate throughout the seasons, once a major bloom occurs, it's very difficult for it to fully clear up without intervention like aeration, vegetation, or other algae-controlling methods.

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