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Does the type of algae and where it’s growing determine what chemical is needed? | Ponds & Lakes Q&A

Q: Does the type of algae and where it’s growing determine what chemical is needed?

Q: Does the type of algae and where it’s growing determine what chemical is needed?

Pete – Addison, AL

A: When battling algae, you have the upper hand if you understand the enemy. What type of algae is it? How does it behave? What are its strengths and weaknesses? Before we get in to how to treat the green menace, let’s discuss the different varieties and where they live in an aquatic ecosystem.

Algae Explained

In a large pond or lake planktonic algae, filamentous algae and chara, are the most common types of algae you’ll come across.

  • Planktonic algae, the source of algae blooms, are floating, microscopic plants that color pond water shades of green, blue-green, brown or variations in between. In controlled amounts, this type of algae can actually be beneficial. It can shade the pond’s bottom, preventing subsurface nuisance plants from growing.
  • Filamentous algae are single-celled plants that form long, visible chain, threads or filaments. These threads, which start growing along the bottom of the lake in shallow water or on rocks or other aquatic plants, intertwine and form mats that resemble wet wool. When these mats rise to the surface, they’re commonly referred to as pond scum.
  • Chara is a gray-green branched multicellular algae that has 6 to 16 leaf-like branchlets that grow in spirals around the stem. Though bottom-growing chara superficially resembles terrestrial plants, it lacks flowers, true leaves and roots. It has a skunky, musty, garlicky-type smell and has a crunchy- or grit-type texture, thanks to calcium carbonate deposits on its surface.

In general, algae will grow just about anywhere sun penetrates the pond. Surprisingly, algae has some benefits: The tiny plants feed fish and make great homes for micro- and macro-invertebrates like bugs and worms. But algae has its definite drawbacks. Besides being unsightly and odorous, uncontrolled blooms can cause oxygen depletions, affect fish health and, in extreme circumstances, cause fish to die.

Vanquishing the Menace

The key to successfully treating algae – whether planktonic, filamentous or chara – is to make the most contact between it and the algaecide. Rather than dumping the chemical into one place in the pond, which will only kill algae in that small area, it needs to be evenly dispersed.

Floating mats of filamentous algae and suspended planktonic algae are best treated with liquid mixtures, like Algae Defense® and Clipper™, that are sprayed directly over the area with a pond sprayer. To treat extra thick mats, stick the top of the sprayer into the mat itself to get the chemical to the deeper portion of the problem.

For bottom-growing algae, use granular algaecide, like Cutrine®-Plus Granular and Hydrothol, and distribute it with a granular spreader. It’s the preferred choice because the granules will sink over the algae bed and make maximum contact with it.

Follow up by raking out any decaying or dead debris with the Pond & Beach Rake, setting up an aeration system and adding natural bacteria, such as the types found in ClearPAC® PLUS Pond Care Package.

Pond Talk: How much time do you spend battling algae in your pond or lake?

Spray Directly Onto Algae Blooms - Pond Logic® Algae Defense®

Now that temperatures are getting warmer, algae keeps growing. How do I stop algae from taking over? | Ponds & Lakes Q&A

Q: Now that temperatures are getting warmer, algae keeps growing. How do I stop algae from taking over?

Q: Now that temperatures are getting warmer, algae keeps growing. How do I stop algae from taking over?

Jeremy – Clinton, IA

A: It sure doesn’t take much for algae to grow out of control! Combine warm sunshine with some algae-loving nutrients and, before long, you’ll have a pond full of pea soup. When it’s thick and dense, those tiny plants can then suck all the oxygen from the water, leaving your fish gasping for air. Plus, it looks bad and can cause some major stink.

For the health of your fish and your lake, you must regain control. Here’s a two-pronged approach that works to eliminate the green stuff and prevent it from taking over.


First, you need to get rid of the algae blooms. For floating algae and chara that’s less than 3 feet deep, use Algae Defense®. The aquatic algaecide comes in a fast-acting liquid formula that can be directly applied to your lake with a pressurized sprayer. If you’re dealing with chara that’s deeper than 3 feet, use Cutrine®-Plus. Its granular formula sinks to the bottom of your lake and destroys the algae.

Once the algaecides start working to kill the blooms, don’t forget to remove dead algae from the pond with a tool like the Pond Rake. If you leave the dead foliage in the lake, will start to break down and become nutrients—or algae food—for new blooms. It’s a vicious cycle!


Now that you’ve got the algae under control, it’s time to get proactive and prevent its future growth. Begin by adding PondClear™ & MuckAway™. These products contain beneficial bacteria that gobble through excess nutrients like suspended organic waste and muck in your pond. The result: Clean and clear water with no noxious odors.

Next, shade the water with pond dye. By preventing the sun’s rays from penetrating the water, you’ll starve the algae of sunlight, which it needs to thrive.


Looking for an easy solution? Check out the ClearPAC® PLUS. This all-in-one algae destroyer contains everything you’ll need to kill the algae and prevent future growth. It contains algaecide, beneficial bacteria and pond dye to fight algae and suspended debris all season long.

Pond Talk: How do you prevent excess nutrients from entering your pond or lake?

Eliminate Algae Quickly - Pond Logic® Algae Defense® & Treatment Booster™ PLUS Combo

Why Does My Pond Water Turn Green? | Decorative Ponds & Water Gardens Q & A

Why Does My Pond Water Turn Green? Why Does My Pond Water Turn Green? 

Joanne – Evans City, PA

Green water is a form of algae called planktonic algae and there are quite a few factors causing your water to be clear during the winter and green as the weather warms up. The main reason is the interruption of the nitrogen cycle.

In order for algae to grow, it needs a food source (nutrients) and sunlight. During the colder winter months of the year, nutrients within the water are less likely to increase due to the fact that the digestive systems of fish have slowed to a point where little, if any, nutrients (fish waste) are being added. Also, during the colder months, algae and aquatic plants are not as active at consuming nutrients.

As the weather warms up, fish become active, digestive systems kick back in and nutrients begin pouring in and if not held in check using aquatic plants, natural bacteria and filtration, green water will develop.

If you have chronic green water and still can’t keep it in check, consider a UV or Ion clarifier.

Aquascape IonGen Electronic Clarifier

Controlling Green Water Algae in a Water Garden – Water Garden & Feature Q & A

Picture of Green Water Algae in a Water Garden.


Water Gardens & Features Q & A

Q: I am having a terrible time with green water in my water garden. What can I do? – Abby of California

A: It’s that time of year again when the fish are playing, flowers blooming and your backyard is once again becoming your peaceful retreat, except for that green water in your water garden. Like most of us water garden owners the highlight of our yard is our water feature but what fun are fish if you can’t see and enjoy them? Here are some considerations that may help you take back your water garden.

Filtration: Early in the season your filtration system may not be up to par with the amount of waste and debris left over from the winter months. A good spring clean out may be needed if there is an excessive amount of debris in the bottom of the water garden. If your water garden is relatively clean use a pond vacuum or application of natural bacteria may help get you on your way. This is the time of year to wash out or replace your filter pads to prepare for the coming season.

Fish Load: Have your fish been busy? If your spacious water garden is becoming a full house, it may be time to find a few friends and share the wealth.  Overcrowding is a common source for green water since the filtration system may not be large enough to handle the amount of waste being produced. A simple rule of thumb to ensure room for your fish is 1 fish for every 10 sq. ft. of surface area.

Plant Coverage or Shade: We recommend 40-60% plant coverage in your water garden. This adds to your filtration, since the plants are up taking their nutrients from the water. They also provide the added benefit of shade to help protect your fish from predators. A variety of plants should be used, including: bog(marginal), submerged, water lilies or floating plants. If your not sure what to get, you can check out our aquatic plant packages.

Help Mother Nature Out with Natural Bacteria: Once you’ve checked your filtration, fish load and plant load, it’s time to add some natural bacteria. We recommend the Pond Logic® DefensePAC®. The DefensePAC® is an award winning water garden care system that comprises of 5 products known in the water garden industry as the 5-Steps to Clear Water. They are:

  1. Oxy-Lift™ Defense®: The Pond Cleaner.
  2. Nature’s Defense®: The Pond Balancer.
  3. Clarity Defense®: The Pond Clarifier.
  4. Muck Defense®: The Muck Reducer.
  5. Seasonal Defense®: The Autumn, Winter Prep.

The DefensePAC® is an all-in-one source for water garden maintenance and will keep your water sparking clear all season….guaranteed!

What about a UV filter?: You might be wondering why UV filtration wasn’t mentioned as a solution to green water. Indeed, it is a solution but…it is also can be a band-aid covering up a deeper problem. Always be sure that your filtration is adequate and you don’t have too many fish! You should also be using your test kitto make sure your water is safe for your fish. If everything checks
out ok a UV may be a good tool as long as it is not the only one. Just remember if everything mentioned above is in check the green water should take care of itself and you will have a healthier overall ecosystem.

POND TALK: What kind of green water problems have you had? And what did you do to fix them? Please comment and let me know.

There is an Oil Slick Film Covering My Pond. How Do I Get Rid of It? – Pond & Lake Q & A

Algae, Duckweed, Watermeal & Pollen Identification

Q: There is a brown rust-like film/oil slick covering my pond. Do you have an idea what this might be and how to get rid of it? – Several Customers

A: There are several things this could be: Algae, duckweed, watermeal or pollen.

Determining if Algae is a Problem: Filamentous Algae will float around the pond’s edges in mats while Planktonic Algae will make the whole body of water to look like a “pea soup” green color. If this is the case, using Algae Defense® Algaecide will provide quick control. Follow up with PondClear™ for long-term clear water.

Determining if Duckweed or Watermeal is the Problem: Duckweed and Watermeal are very rapid growers and will cover an entire pond if they get out of control. Looking to the pictures to the left, you can see that Duckweed is a small plant the size of a pencil eraser, while Watermeal is about the size of the tip of a pencil. If you determine that you have Duckweed or Watermeal. Your only long-term option is Sonar™ A.S. for Duckweed and Clipper™ for Watermeal. If you only require short-term control (3-4 weeks) for an event or party Ultra PondWeed Defense®” may be used.

Determining if Pollen is the Problem: What may look like a greenish, brownish algae, may actually be pollen. Pollen may even cause an oil-slick or film on the surface of the pond. There is no magic product that will give you a quick fix. Many times a heavy rain will settle it to the bottom. In many cases if your pond receives good circulation from an aerator or fountain you will not see pollen becoming much of a problem.

Controlling Pea-Green Algae – Water Garden Q & A

Q: I have a pea-green algae problem. What is the quickest, safest way to overcome this problem? -Ruth of Starkville, MS

A: When dealing with planktonic algae or “pea-green algae”, it cannot be simply eliminated using a product like AlgaeFix®. AlgaeFix works great on string algae or other patches of free-floating algae, but with planktonic algae, there is so much that you run the risk of depleting oxygen levels to a point that is unsafe for fish. One of the best ways to get rid of this type of algae is through the use of a UV Filter. As the planktonic algae passes throught the ultraviolet light, it will die. UV lights work so well that within just a few days your water will be crystal clear.


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