Using Barley Straw As A Blanket Weed Treatment


Everyone is looking for ways to accomplish jobs once handled by chemicals or physical labor in a more environmentally favorable, and less labor intensive way. One such treatment for filamentous algae (also known as pond scum, blanket weed, pond slime and other names) problems is the use of barley straw. Barley straw has been shown to prevent "blanket weed" or filamentous algae when used properly in ponds. It is thought that the decaying barley straw produces an enzyme that prohibits algae growth, but most experts will tell you that they honestly don't know exactly why.

What are the good and bad points of using barley straw?

The good side of barley straw treatment is that it is organic, and no chemicals are involved in the process, so there are no toxicity issues for fish or human beings, and that it seems to work fairly well. The bad thing about barley straw is that it is organic, and adding organic material to ponds is not always a good thing. To much decomposition can rob the water of oxygen, and add too much nitrogen. Both of these are bad for a pond. There are a few other issues. Barley straw may help to prevent pond scum, but it will not kill what is already there, and it may cause problems with the ponds natural life cycle if it destroys plankton. Plankton feeds the tiny creatures that feed fish, and without it, the fish go hungry. Furthermore, the destruction of the suspended plankton in the water will clear the water, something which unknowing pond owners desire, but which will allow light to reach the bottom where the pond scum starts, encouraging a new round of invasions from filamentous algae and lake weeds! The only way to keep pond scum from the top of your lake is to prevent sunlight from reaching the bottom of your lake, and that is accomplished best by healthy algae bloom. The same is true for most blanket weed treatments. An algaecide will kill algae indiscriminately, leaving no suspended plankton in the water profile. If the water is not more than 3 feet deep, and no follow up is done to produce algae bloom, the problem may come back with a vengeance! If barley straw is successful in preventing all forms of algae, there will be no algae bloom, or plankton to feed the small invertebrates that provide food for the fish.

When would barley straw be a good option?

The use of barley straw may be just the ticket if you want a clear pond with few fish, or if you want a clear pond, and you regularly feed your fish. The barley will need to be replaced periodically, and you may have problems with some aquatic weeds as a result of the water clarity issue, so be prepared to deal with them.

More natural methods

There are other ways to approach the problem of blanket weed. It can be prevented with algae bloom, which will further the life cycle. I know that it seems a little odd to use one type of algae to prevent another, but it is the best preventive method, and is perfectly natural. Most of the ponds and small lakes throughout the country are man made, and do not have the native fertility of natural lakes. In most natural lakes, the natural fertility allows a pretty constant algae bloom, coloring the water with a green tint, preventing light penetration to the bottom where the blanket weed and other aquatic weeds starts, and keeping the life cycle of the lake in operation. With man made ponds, in some areas, that native fertility may not exist. In such cases fertilizer may need to be added on a regular basis to acheive the same result. A good pond fertility program may be the most environmentally friendly and effective way of dealing with blanket weed. See also: Barley Straw Pond Algae Control: How To and Barley Straw Pond Algae Treatment Drawbacks and How To Fertilize A Pond Or Lake

How The Parts Of Ponds And Lakes Interact


All of the parts of your pond or lake interact with all of the other parts. Each problem you have is a part of other problems, probably leading back to a single problem at some point. pH, lake fertility, dissolved oxygen levels, fish size and weight, and lake vegetation each have something to do with the other, therefore, it is important to trace any problem back through each factor, and find the primary cause. As an example, we have a 4 part series about how these interactions occur. Pond Scum Lake Weeds Mosquitoes And Skinny Fish Controlling pond scum, lake weeds and mosquitoes and raising healthy fish may seem complex and difficult. There is no miracle cure, there is no magic bullet. Pond Scum And Lake Weeds Most of the questions we receive about lake weeds revolve around how to get rid of them. As with pond scum, most lake weeds get their start at the bottom of the pond when sunlight reaches them. When conditions are right, they may grow out of control causing problems for the pond owner. Mosquitoes And Skinny Fish Mosquitoes on ponds and lakes may seem to be unrelated to lake weeds and filamentous algae. The truth however, is that mosquitoes become a problem when there is too much vegetation in the pond... If the water has too little of one type of algae, and too much of another, the ponds life cycle is interrupted, and the fish go hungry, resulting in skinny fish. Pond Scum And Lake Weeds The Real Problem The problem is sunlight. You can’t do much about that. Specifically, the problem is sunlight reaching the pond bottom, which you can do something about!

Pond Scum And Lake Weeds The Real Problem

Part 4 in our series on lake and pond interactions

The real pond scum and lake weed problem


The problem is sunlight. You can’t do much about that. Specifically, the problem is sunlight reaching the pond bottom, which you can do something about! The common issue for pond scum and lake weeds is sunlight penetrating the water to the bottom of the pond or lake. When this happens, a process begins which will allow lake weeds to grow unchecked, pond scum to develop and start to rise to the top, and the secondary result will be mosquitoes, and even though the plants and algae will produce oxygen, they will at some point cause conditions which will deplete oxygen in the water, and all the while, your fish will be starving. All of this because sunlight reaches the pond bottom!

Preventing lake weeds and pond scum by preventing light penetration

There are a number of ways to prevent light from reaching a pond or lake bottom. You can raise the water level, lower the bottom through dredging, or color the water in some way. Raising the water level can produce good results in some cases, but may not be practical, and it still doesn’t deal with the issue of skinny fish. If the water is deep enough the sunlight cannot penetrate, but something needs to be done to feed the fish if the water is clear to a depth of more than 24 inches, so even if you can raise the water level, or dredge the shallow areas, more is needed. The water needs color to shade the bottom. This can be done with dyes and colorants, but, once again, you still have the issue of skinny fish. There is a product that can resolve both the light penetration issue, and the food supply issue.


Plankton is a single cell algae which is suspended in the water of healthy ponds and lakes. It provides oxygen to the water, food for the tiny invertebrates that feed the larger aquatic life, which ultimately feeds the fish in the lake, and provides color for the water helping to prevent the excessive growth of unwanted vegetation and pond scum. This is sometimes called algae bloom.

Producing algae bloom

The reason that plankton does not grow in a pond or lake is lack of fertility. The solution to this problem is to add fertilizer. To learn more about this process see: pond scum prevention and Lake weed prevention Pond scum is filamentous algae, and is also known as blanket weed, pond blanket weed, and a few, less desirable terms.

Pond Scum And Lake Weeds

Part 2 in our series on lake and pond interaction

Pond scum control


Most of the questions regarding pond scum, lake moss, or pond algae ask how to get rid of it. This is perfectly logical. The problem is, that the pond scum itself  is just a symptom of other problems. The first evidence we have of it’s existence is when it floats to the top and interferes with the aesthetics, our recreation or our fishing. Filamentous algae, or pond scum as it is more commonly known exists in most bodies of water, and will begin to show itself when conditions are right for it. It grows from the bottom, and sunlight allows photosynthesis when it penetrates to the bottom. The photosynthesis process allows the algae to take in carbon dioxide, and exhale oxygen, some of the oxygen, which is good for fish, will be released under the algae mat, and gradually cause it to float to the top, where it becomes a nuisance.

Lake weed control

Most of the questions we receive about lake weeds revolve around how to get rid of them. As with pond scum, most lake weeds get their start at the bottom of the pond when sunlight reaches them. When conditions are right, they may grow out of control causing problems for the pond owner. Some aquatic weeds are capable of doubling in mass in a week or less, leaving the pond owner with a huge aquatic weed control problem. If measures are taken to kill the weeds with aquatic herbicides, the weeds will die, and drop to the bottom where they will decay over time. This can produce a slimy, and high organic fertility on the pond bottom, perfect to supply nutrients to the next generation of weeds!

Mechanical lake weed control

Mechanical controls and mechanical lake weed harvesting may produce less slime at the bottom, but care must be taken when using a lake weed cutter to collect all the fragments, as aquatic weeds are notorious for their ability to reproduce from fragments. One plant chopped into 100 pieces may turn into 50 new plants in a matter of days. See: The relationship between excessive aquatic vegetation, Mosquitoes And Skinny Fish

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.

Pond Scum Control Advice


Filamentous algae, otherwise known as pond scum, is a nightmare for many pond and lake owners. The pond scum problem has a lot in common with other types of lake vegetation problems, and the cure for one will probably cure both. So, how do you get rid of pond scum? There are a number of different treatments, but the best method for dealing with pond scum is to prevent it from starting, and the method of prevention may come as a bit of a surprise.

Pond scum treatment

Pond scum, no matter where it ends up, starts at the bottom of the pond or lake. Pond scum is noticed most often on the surface of the lake or pond, but like emergent, or submersed lake weeds, it has its start on the lake bed. Pond scum treatments usually involve the use of a copper substance in liquid or granular form, or a contact weed killer like diquat. These products kill the algae, by punching tiny chemical holes in it, and the pond scum loses it's buoyancy and drops to the bottom. If you have this problem over a good portion of the lake or pond, it is best to treat only one third to one half of the lake at a time because the rotting vegetation requires oxygen to decompose, and it will take it from the water, which leaves less oxygen for your fish.

Pond scum removal

It is possible to physically remove pond scum from the surface of the water, but this process involves a good deal of manual labor in either skimming, or raking it. If you use copper sulfate or one of the other commercial herbicides labeled for pond scum or blanket weed control the algae will turn brown and sink to the bottom where it will degrade on it's own. Be aware that if you do not perform proper follow up procedures, the filamentous pond algae will return! Treatments of this type are sometimes needed, but such pond treatments are like the emergency room doctor after an auto accident. We are glad that he is there, but, it would have been better to have avoided the accident to begin with.

Preventing pond scum

Pond scum starts at the lake or pond bottom, it begins when sunlight penetrates to the bottom. Preventing light from reaching the bottom will prevent pond scum in the majority of cases. The prevention of pond scum, like the prevention of lake weeds requires doing something that will keep sunlight from reaching the lake bed. This involves water depth, and water clarity.

Adjusting water depth

There are two ways to change water depth. Raise the water level by adding water and maintaining it at a higher level, or removing soil from the bottom.

Raising the water level

Any attempt to raise the level of a spillway or overflow pipe should be preceded a thorough inspection  of the lake by someone who has the expertise to determine the success of such a project.

Removing soil from the lake bed

The other method for adjusting the depth of water in a pond or lake is to remove soil from the lake. This dredging process can be accomplished by draining the body of water and using earth moving equipment  to remove sediments, or by leaving the water, and hiring someone with specialized equipment built for the purpose. Either way, the project will be costly and time consuming. Ideally, there should be no area of the lake or pond that is less than 3 feet deep.

Adjusting water color

If water is too clear, then enough light can penetrate to produce filamentous algae. If sunlight can penetrate more than 24 inches, the water is too clear. There are colorants available which can do the job, but such colorants interfere with the natural food chain in the lake. The best means of producing color in a pond or lake is with tiny single cell algae known as plankton. Producing an "algae bloom" will reduce the depth to which sunlight can penetrate water, and prevent pond scum from becoming a problem. This is something that should be done even if your pond or lake is deep enough already. It will encourage the food chain and provide more healthy fish for your recreational fishing and for the table.

How to produce algae bloom

To start algae bloom, all that needs to be done is to add the proper amount of the proper fertilizer to the water. This should be done only after testing the water for proper pH, and amending the pH if needed. Once this is done, and the fertilizer added, the reaction will be swift. This should be followed by regular applications at 2 week intervals, and water clarity should be tested to be sure that it is working, and that water clarity is no more than 24 inches, and no less than 12 inches. If secchi depth is less than 10 to 12 inches, skip the next fertilizer application and re check the clarity periodically until it gets into the acceptable range before re starting the program.

Natural pond scum prevention with barley straw

There is evidence that pond scum can be prevented by using barley straw. The straw is submerged, or partially submerged in the water, and the decaying barley straw produces some chemical reaction that is not yet fully understood, but which seems to discourage filamentous algae production. It should be stated again, that this is not a treatment for existing pond scum, but another tool in our pond scum prevention kit. Remember that any algaecide, including barley straw is indiscriminate in pond algae destruction. When the pond scum is destroyed, there is a good chance that it will destroy the beneficial pond algae as well. Follow up is essential for for healthy ponds and lakes. For a paid consultation about dealing with your pond scum problem see:

Lake Consultation