Did your nice clear pond seemingly turn green overnight? You may need to get rid of algae in your pond!
If you’re experiencing an algae bloom under the right conditions, your pond water may become turbid and colored within just a couple of days.
Some people wonder if it’s really that big of an issue.
Algae grow there naturally — shouldn’t it be fine to leave?
No, algae growth can take over your pond just as quickly as it appeared, starving fish and plants of essential oxygen and nutrients.
But how do you get rid of algae without killing all other living things?
Here’s everything you need to know about getting rid of that green water in your pond.
1. What are algae?
Algae are simple, non-flowering, primarily aquatic organisms.
Algae lack true roots, stems, leaves, and the multicellular reproductive structures of plants.
2. Why do algae grow in ponds?
Algae blooms often occur when a pond has an imbalanced ecosystem.
A common cause of this is fertilizer runoff adding too much nitrogen or phosphorous.
If you’re applying fertilizer to your grass or plants surrounding the pond, then you could be inadvertently causing algae.
3. What are the three types of pond algae?
The three types of pond algae include cellular, string, and matted.
You can identify each of these by the way they look.
Cellular, green algae look like pea soup.
This type of algae consists of single-celled organisms that remain suspended in water.
These organisms are so tiny that they pass through fine filters.
If there are enough nutrients and sunlight, then up to five million algae cells per millimeter of pond water can exist.
String algae is a species that grows in long strands, so it looks like long green hair.
This type adheres to rocks and waterfalls.
They’ll form thick, unsightly mats that tangle together and double their weight within 24 hours.
Matted algae look similar to string algae, but grows in dense, spongy mats.
It forms when alternating layers of blue-green bacteria and sediments are either deposited or grow in place.
This creates dark-laminated layers.
4. What are the signs of algae problems?
The presence of algae in the water is not inherently a problem.
However, it’s often an issue in ponds because they don’t allow other organisms to get the oxygen they need.
Here are some signs that algae are having harmful impacts on your waterbody.
You’re seeing dead fish or waterfowl in your pond
You’ve had pets get sick or die on your property
Your water smells foul
You’ve experienced skin rashes after contact with the water
5. How do you get rid of algae in ponds?
There are multiple ways to get rid of algae growing in your pond.
Before acting, you should consider if you’re interested in a chemical or chemical-free option.
The option you pick will likely depend on what else exists in your pond and how long-term you want your solution to be.
We’ll cover both solutions below.
6. What are chemical-free ways to get rid of algae in ponds?
If algae growth has long been an issue in your pond, you should consider treating it without chemicals.
Chemicals can help to remove algae initially, but they won’t prevent regrowth.
Here are some methods you can use to help get rid of algae naturally.
Plants
Plants are a natural way to help balance out the nutrients that are produced by fish that can cause algae.
You should add plants to a pond whether you’re looking to avoid algae in the first place or you want to get rid of what already exists.
Numerous oxygenating plants on the surface of the pond are one of the simplest and longest-term solutions to keeping water clean and clear.
Here are some ideas of what you should buy.
- Floating plants — lilies and lotus
- Submerged plants — anacharis, hornwort, parrot’s feather
UV Clarifiers
A UV clarifier is a great way to eliminate discolored water caused by algae.
If your pond is in full sun, they can help combat excess sunlight and destroy ultrafine particles that cause discolored water.
Once they’re killed, these dead particles will clump together, and the mechanical filter will remove them.
You should consider your pond and pump size when choosing a UV clarifier.
If your pump is too large, then the particles won’t be exposed to the UV radiation long enough to damage the cell walls.
You should also keep in mind that the pond UV light bulbs must be replaced each year.
Even if the bulbs still light up, they become less effective over time which means they won’t be able to control the discoloration of the water.
Copper ionizers
This solution is designed to release ions into the water, which helps keep it clear and reduce string algae buildup.
You can incorporate ionizers into new or existing ponds under a few circumstances.
First, you must install them in line with plumbing or place a drop-in model into your pond skimmer.
Next, you should ensure that your pump has at least a minimum flow rate which is required for ionizers to work.
Barley
Barley can help you maintain a clean and clear pond naturally.
If you have a pond with fish and other wildlife, you should consider using barley because it won’t harm them as chemical options will.
Additionally, barley can be used during the winter months when other treatments are often ineffective.
You can find barley in different forms like extract or pellets.
The type you choose to use will come down to preference as both are effective.
Beneficial Bacteria
Because excess nutrients and sunlight are the normal cause of algae blooms, you can try using beneficial bacteria to counteract these effects.
The beneficial bacteria will consume the nutrients and other organic material in your pond and convert it to harmless gas.
You should see a difference for up to six months and your pond if you decide to go this route.
High-quality fish food
Invest in high-quality fish food that will be fully digested.
When your fish digest more nutrients, it leaves fewer to pass through the fish and causes algae.
Garden hose, hand, or net
If your pond is struggling with string algae, you’ll want to use old-school methods like a garden hose, hand, or net.
The hose will be helpful to blast it off rocks and waterfalls where it often accumulates.
You can also remove it by hand or net.
7. What are the chemical methods of getting rid of algae?
There are several methods of pond algae control that utilize chemicals.
This isn’t the ideal solution for landowners who want to go the natural route, but it’s often the easiest method available.
Here are some various methods:
Mizzen is a copper-based algaecide that helps control nearly all types of Planktonic Algae, Filamentous Algae, and Chara.
This product is safe for some fish but not all.
Do not use it if you have a pond with Channel Catfish, Koi, or Trout.
Cape Furl is a fish-safe algaecide.
If you want to remove algae from your pond without harming your fish, this is a good route to go.
8. How do you apply chemical treatments in ponds to get rid of algae?
If you decide to use a chemical treatment like Mizzen, how do you apply it to your pond to get rid of algae blooms?
First, you should always follow the manufacturer’s instructions for dosage rates.
They can help you get the best results.
However, we’ll include some additional guidance below.
If you’re experiencing frequent and recurrent algae blooms in your pond or lake, re-apply Mizzen every 2 to 3 weeks.
You can help reduce severe algae blooms by avoiding oxygen depletion.
To do this, apply Mizzen to only one-half or one-third of an area at a time.
After doing this, you should allow 10 to 14 days between the applications.
Before you apply an algaecide, you should break up any large mats to ensure maximum efficacy.
If possible, apply Mizzen as soon as algae appear.
Just make sure the water temperature is above 60 degrees Fahrenheit!
9. How do you prevent algae in the first place?
As noted above, a lot of algae issues stem from excess nutrients in a body of water.
These nutrients can come from a variety of sources, such as lawn fertilizers, grass clippings, decaying leaves, goose droppings, leaking and failed septic systems, rain run-off from high nutrient areas, etc.
If you’re struggling with algae in your pond, you should start by controlling the source of nutrients.
Try to pinpoint where these nutrients could be coming from so you can address the root issue of the cause.
Additionally, you can help to prevent algae through the following methods:
Not overfeeding any fish or waterfowl as this will result in excess nutrients
Purchasing high-quality food that will feed your fish or waterfowl efficiently
Planting or maintaining native flora that grows around the pond
Avoiding the overuse of lawn-care products
Not allowing pets to defecate in the pond
Limiting your pond’s sunlight by adding a sun sail or umbrella
10. What are tips to clear algae from the water fast?
If you hate the presence of unsightly algae, here are some steps you can take.
Manually scrub the sides of your pond with a new toilet brush
Rinse your garden pond filter daily
Use hydrogen peroxide to help clear the water (it won’t harm your fish!)
11. How do you know if the algae are planktonic?
You likely won’t know if your algae are definitely planktonic because planktonic algae can only be identified under a microscope.
That said, the abundant growth of planktonic algae is usually easy to identify visually.
It appears as a paint-like scum on top of the water’s surface and is normally described as “pea soup.”
That said, this type of algae can often be mistaken for growths like Duckweed or Watermeal.
12. What are the steps to removing algae?
If you’re searching for a step-by-step guide, keep reading.
If you’ve inherited a pond that has a lot of algae in it or you were complacent about maintenance, here’s how you can get it taken care of.
Step 1: Identify the algae growing in your pond
Above, we named the three main types of algae: cellular, string, and matted.
The removal method will depend on the type of algae.
Step 2: Determine the best removal method
- Green algae: Use a UV light that will zap the algae in suspension continuously without harming your fish
- String algae: Manually remove the algae from your pond with a rake
- Matted algae: Manually remove the algae from your pond with a rake
Step 3: Prevent the algae from coming back
Okay, you’ve officially gotten rid of the algae in your pond (hooray!).
How do you keep your pond clean and clear from here on out?
The best way to do it is by keeping your nitrates and phosphates in check.
These are your algae’s food source, so if you can eliminate them then you can eliminate your algae.
Phosphates are often found in water sources, so it can be a difficult issue to address.
However, if you’re feeding your fish a high protein diet, you could be inadvertently elevating your nitrates.
You should also monitor how much sunlight your pond receives.
Algae love sunlight, so you’ll need to use some tactics to keep your pond in the shade.
Doing this can also stabilize your pond’s temperature and prevent UV damage to your fish, which is a big bonus!
Final Thoughts
Just because your pond has algae in it now doesn’t mean it has to stay that way.
Use the tips above to salvage your pond.
Algae steal nutrients from fish and plants, which means you must intervene, or you risk losing an asset to your property.
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Disclaimer: we are not lawyers, accountants, or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.
Prior to starting Gokce Capital, Erika received a Bachelor of Architecture from the University of Southern California and a graduate degree in Urban Policy from Columbia University. She worked as both an architectural designer and engineer in New York before joining the New York City Department of Housing Preservation and Development.
Erika currently lives in the New York Metropolitan area with her spouse, daughter and cat. She is originally from Chicago and still considers herself a midwesterner at heart.
Erika also loves to read, write and travel (fun fact, she has visited all 50 states and more than 30 countries!). Her new book, Land Investing Mistakes: 11 True Stories You Need To Know Before Buying Land, is now available on Amazon.