How Can I Prevent Pond Algae?

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Not all algae is bad First, let's get our minds wrapped around this: Not all algea in ponds and lakes is bad. The problem comes when you have too much algae, or the wrong type of algae. In fact, the best treatment for pond algae, is algae! I know it sounds a little strange, but that is the way it works. What is pond algae When most people think of pond algae, they think of the type of algae commonly called pond scum, or blanket weed. The proper name for it is fillamentous algae. This is a type of algae that forms long fillaments or strings that then mat together to form a blanket on the surface of the water. This mat or blanket of algae makes fishing, boating, and other recreational use of a lake or pond difficult and distastefull. Pond scum also allows a perfect environment for mosquito production. In general, blanket weed in a lake is not a good thing for human use and interaction with the lake. Understanding pond algae To understand the best treatment for it, we need to understand where it starts, and how it starts. When we notice pond scum, we notice it on the top of the water, but that is not where it begins. Fillamentous algae starts at the bottom of your reservoir, and rises through the water profile as it gains bouyancy from the oxygen it produces. Eventually, enough oxygen is produced to lift it to the top of the water where it floats annoyingly. Clear water is the problem The problem is not that your pond or lake water is too murky, the proble m is that it is too clear. Again, I know that this is counter intuative, but bare with me. You have probably heard someone say "I can't see through muddy water." when they wanted you to move out of their line of site. The same principle applies here, because light penetrates straight through clear water, and because sunlight is needed for plant production, if the water is not clear, plant production is limited. If your water is too clear, you will have pond algae. The answer is not to go out and make the water muddy, the answer is to produce a single cell algae known as phytoplankton to tint the water, and prevent sunlight from reaching the bottom. So how do we prevent pond algae? Pond fertility is the answer. Check your pond or lakes water. If it is clear to a depth of more than 20 inches or so, it is too clear, and chances are, your fish are going hungry as well. A good fertilization program will solve both problems, and many others as well. This is how it works: When the proper amount of the proper fertilizer is introduced into the water, in the proper way, the single cell algae known as phytoplankton will reproduce rapidly in a process called algae bloom. This will continue as long as the water is fertile. The green color, or the golden brown coloring that this method produces will tint the water, preventing sunlight penetration, and preventing the growth of fillamentous algae. To learn how to do this see these pages, How To Fertilize A Pond Or Lake Lake Fertilization Lake Management Lake Weed Control Water Depth Secchi Depth and all the posts in this section of Home And Garden Press: Lake Management

Pond Scum Prevention Pond Algae

Pond Scum Prevention Pond Algae


We are all aware that pond scum may be the secret of the fuel production of the future, but in the mean time, it is probably not something you want in your recreational fishing pond. For one thing, it is ugly, for another, it is often stinky, and to make matters worse, it can do harm to other forms of aquatic life, and harbor potential disease carriers like mosquitoes. Not all algae is bad, but an abundance of blanket weed pond scum, almost always has an adverse effect on aquatic life. You can find the proper distinction between the filamentous pond algae that plagues pond owners, and the types of algae necessary to maintain healthy pond life below.

What causes pond algae?

Algae is always present, but what causes it to spring up in such dramatic fashion in the spring and summer? The best answer is sunlight. Pond algae starts in the bottom of a body of water, in spite of how it may appear. The floating mass you see at the top of the pond is algae that started on the bottom, and gained buoyancy as it took on air, and floated to the top in the stinky familiar mass. Sunlight penetrating to the bottom of a pond starts the photosynthesis process, and kick starts the whole nasty mess.

Different types of pond algae

So, is all algae bad? The answer is a resounding NO! In fact, the best means of preventing pond scum, or filamentous algae, is by producing another type of algae. Plankton. This single cell algae will remain suspended in water, providing food for the tiny animals that provide food for the larger life forms, which in turn, provide food for your fish, and, if you are a successful angler, food for you.

Pond algae control using algae

Not only does this type of algae feed the fish, it also colors the water. That nice green or blue green tint that you see in healthy ponds and lakes is suspended algae, and one of the best services it provides is tinting the water, thereby preventing sunlight from reaching the bottom of the lake or pond, preventing the growth of unwanted vegetation, and providing pond algae control. Yes, pond scum, like most aquatic plant life, gets it's start at the bottom of the pond, and as it gains oxygen, it floats to the top where it produces all sorts of undesirable conditions, like the ones mentioned above, and including lousy fishing conditions, oxygen deprived fish, and frustration.

Algae for tinting the water

Getting rid of the pond scum type of pond algae can be a difficult task, and if the conditions that allowed it are not changed, it will return. Remember, the problem is sunlight reaching the bottom of the pond, so something must be done to prevent it from doing so. This could include raising the water level, which may not be possible in all cases, dredging or otherwise making the lake deeper, or coloring the water. The last, is usually the chosen option. There are dyes which can color the water, but, if fish production is what you desire, remember that dyes do not feed the fish. In small ponds for catfish production, where regular feedings occur, this may work, but where no feeding takes place, or where other types of fish are desired, dyes are not the answer. Once again, plankton is needed to continue the life chain, and prevent the pond scum problem.

How to produce plankton to prevent pond algae

So, how do we produce this plankton? The answer is simple: Fertilize the pond. Now before you start thinking that it is a crazy idea, let me do a little explaining. Fertilizer, usually a fertilizer high in phosphorous, will encourage algae production through a process known as algae bloom, and this will produce the coloring needed to stop pond scum. There are a few things you need to check before you fertilize.
  • First, get rid of the existing pond scum, and give it time to decompose.
  • Second, test the water pH. Anything lower than 6.8, and you need lime to raise the pH. Something between 6.8, and 8.6 is ideal. If it needs correcting, correct it before proceeding.
  • Third, check the secchi depth. It should be between 18 and 24 inches. If the secchi depth is less than 18 inches, there is another problem. If it is more than 24, begin fertilizing as soon as possible, and continue the process throughout the summer, or until the depth is less than 18 inches.

Other factors

There are other factors, like muddy water, which will need to be solved before pond algae treatment, and you will need to know the details like how to use a secchi disk, and how much fertilizer, which are covered in other places on this website. See: How To Fertilize A Pond Or Lake Note: Filamentous algae goes by many common names: Pond algae, pond scum, pond slime, pond blanket weed, string algae, and others. There are other types of algae present in many ponds, some of them are beneficial to the ongoing health of the pond. Chief among these is the algae known as phytoplankton or simply plankton, the simple single cell algae that is suspended in water, and produces food for the life chain.