Pond scum, it goes by a lot of different names, but most of the time, it is really a type of algae known as filamentous algae.

Algae, are very primitive plants, there are several types, including the planktonic algae that is often suspended in the water profile of a pond or lake, and gives it that green tint that we are all familiar with. It is a single cell, that feeds aquatic invertebrates, which, in turn, feed larger creatures and so on up the food chain.

There are more advanced forms of algae as well, such as “Nittela”, and “Chara”, which resemble vascular rooted plants.

Filamentous algae, or pond scum starts growing at the bottom of a body of water, and gradually moves to the top by virtue of the buoyancy it provides through the creation of oxygen by the process of photosynthesis.

Pond scum, algae

The best “green” aquatic weed control.

The very best, “greenest” method of controlling any pest, animal or vegetable is prevention. In terms of aquatic weeds that means a lot. If you can prevent anything, it is much better than treating or managing it later. That should be a “given”. Avoiding infestation by being vigilant in inspection and cleaning of boating equipment, making sure that there is a sufficient amount of suspended algae in the water to prevent sunlight from reaching the bottom, and if needed, and practical, raising the water level, or making the edges deeper by excavation are all good prevention measures.

Is biological control always “green”?

Often, biological controls for insects and weeds are considered “green,” just because they are biological and not chemical. This is not always the case. You have to look more deeply into the anatomy of the situation. A biological control is most often a natural predator from the plants native area. If the plant we are trying to rid ourselves of is an exotic, we are introducing another exotic into our native environment.

Most of these are studied by our top scientists to insure that they will be safe, but there is always a chance that an unknown factor could be missed, or that the situation could change, and that the new predator we have introduced to get rid of the problem, becomes a problem itself! As far as biodiversity is concerned, biological controls may be the least environmentally friendly.

What is the “green” potential for other methods of dealing with aquatic weeds? The answer might surprise you!

What about mechanical control?

Mechanical controls that cause fragmentation can cause the spread of most aquatic plants therefore, from the biodiversity standpoint, they are problematic. If done properly with the proper equipment, and at the right stage, they can be very helpful.

Chemical control.

Oddly, chemical controls, though seen as the least environmentally acceptable form of control by many, may pose the least threat to the environment. Unlike the biological controls which might have some unknown factors, chemical controls are a known quantity and can be handled accordingly. They are less likely to cause the infestation to spread than mechanical controls.

If you have made it through the rest of the steps in this guide, you should by now, have a nicely vegetated pond,

As I said at the beginning, you cannot hope to support any bass in a pond that has no more than a surface acre of water. The best fish for a small pond, is catfish.

Adding a batch of fathead minnows will help to increase the yield.

The idea of fertilizing a pond seems strange to many people, but is something that may need to be done.

Fish

Flocking:

Fertility

Checking pH is a simple matter of getting a cheap testing kit, and testing the water.

You can buy one at some of the major discount stores, or a pool supply place for a few bucks. It will be very handy for you.
pH should not be below 6.8, or the water will not support the algae bloom necessary to support the aquatic invertebrates (bugs) needed to help support the fish.
If the pH is not high enough, you will need to use an agent, usually agricultural lime, to get it higher.
How much you will need to use, is dependent on the pH, and the area to be covered. In general, from 1 to 4 tons of agricultural lime is applied per acre. Liming can be difficult work, but it is well worth the effort if needed. It will make every other aspect of your lake or pond management work better. There are some products becoming available which should make lime applications a little less labor intensive.

How often must I lime?

pH should be tested on a regular basis, but re-liming may not be needed each year. One treatment can last for 3 to 5 years. There ares some cases however, where annual re-liming would be desirable. In such cases smaller amounts of lime are needed per application, usually about 25% of the original application.

Next:

Managing Water Clarity

Turning Your Pond Or Lake Into A Fishery

Part 1

Turbidity

Eutrophycation

Next: Pond pH Part 2

Sometimes it becomes necessary to use some method of control to deal with aquatic vegetation. Most texts list 3 types of control, mechanical, biological, and chemical. I have a fourth which is the very best form of control for any unwanted organism which I will list .

• Mechanical aquatic weed control.

Mechanical lake and pond weed control is the physical removal of the plant. This can be manual or mechanical, and include cutting, pulling, and raking. The major problem with mechanical controls comes in the form of fragmentation. Most aquatic weeds can reproduce from small fragments, so that if the parent plant is not removed or killed, there will be more plants added to the already existing ones. Other mechanical management methods include draw downs, and dredging to make the water deeper and less susceptible to plants needing sunlight.

• Biological aquatic weed control.
  

Biological pond and lake weed control involves the control of vegetation through living organisms. To date, these include some weevils, and a few types of fish such as tillapia and white amur, and a few other types of plant pathogens. Biological controls are the least predictable form of vegetation control and can present a number of potentially serious problems.

• Chemical aquatic weed control.
  

Chemical controls involve applying chemicals to destroy plants. They can be somewhat selective, as in killing only broadleaved plants or emergent plants, and can be applied in such a way as to destroy plants around a dock or ramp, and leave plants in a shallow slew.

Proper identification of aquatic plants.

The most important aspect of any of the three above mentioned methods, is to properly identify the plants that you are dealing with. This is a very detailed study, but there is a fine tool available for the identification of aquatic plants, and information on treatment methods. Aquaplant is a service of Texas A&M, and can assist you with many of your lake or pond management issues. I use it myself.

• Prevention of aquatic weeds.
  

Prevention of lake and pond weeds. This should be seen as the holy grail of control techniques. Prevention may involve the use of some of the other methods, such as dredging the edge of a lake or pond to make the water deeper, and prevent sunlight from reaching the bottom. It can involve fertilizing to provide algae bloom which will block the sunlight from reaching the bottom, and in some limited cases, the addition of colorants for the same purpose.

The major effort in prevention is to keep invaders out. this involves thorough cleaning of all things that go in or near the water before moving from one lake to another.

Managing pH

Some sources say that there are 4 types of aquatic plants. Submersed, emergent, immersed, and floating. Here again, the categories don’t entirely work.

For our purposes, we will list 3 types:

• Submersed plants are those rooted plants which exist under the water in normal conditions.

• Emergent plants are those that grow in the soil beneath the water, and whose tops protrude from the water. Sometimes, plants that are widely considered to be submersed, have tops that rise out of the water as well.

• Floating plants are the plants that normally float without connection to the bottom.
  

I would narrow the categories a bit, and use the standard normally used for terrestrial vegetation. We can say that there are two types of plants, broadleaves, and grassy, which can help us know what treatments will be most effective, but there are points where this analogy breaks down.

Next: Aquatic weed control types.
More on floating and emergent aquatic plants