Trouble shooting for an existing pond
by Dave Breiter, Petstore Staff Member

No matter how well designed and thought out a pond is there is always something that either was overlooked or isn’t going as planned. Through proper design and construction we try to limit these variables but it’s rare to catch them all. Every pond experiences its share of problems at some point. This section is designed to list as many of those common problems faced by pond owners as possible along with the best methods for solving them. There is no sense in going through the headache of trial and error for a problem that someone else has already dealt with. Be thankful that someone else has experienced these problems, solved these problems, and posted them here for you to take advantage of.

How do I control the algae in my pond?

Algae is the most common problem faced by all pond keepers world wide. Just about every pond has some form of algae growing in it. In many cases algae is an encouraged benefit within the balance of the pond. It’s when the algae exceeds that balance that trouble ensues. It’s a constant battle that has been raged since the beginning of ponds, pond keeper vs. single celled plant life. Sounds like we should win hands down; unfortunately that’s not usually the case. Algae has gotten the best of many good pond keepers and discouraged them into submission. Fortunately we do have the knowledge to win. It’s just a matter of time and effort in becoming familiar with your enemy; learning its tactics, strengths, and weaknesses. With knowledge you can strike hard, fast, and with success. That’s what this section is designed for. Here you will gain the knowledge that is necessary to control the algae in your pond and keep it at a beneficial level

Understanding what causes algae

With few exceptions algae requires three things to grow and flourish: water, light, and food. These three things make up the minimum requirements for algae to survive. Obviously, in a pond setting water is in extreme abundance. Since the majority of ponds are outdoors they are exposed to sunlight which provides an abundance of light also. Even indoor ponds and shaded ponds receive plenty of ambient light to create, what algae would consider, an abundance of light. That leaves one last parameter, food. What does algae eat? Algae consumes biological waste which is dissolved within water, namely nitrogen products such as nitrite and nitrate. This should make sense to those of us who are gardeners. Algae is a plant, plants consume and flourish on fertilizer, fertilizers contain nitrogen products. If algae is provided an abundance of any of the three or any combination of the three requirements it will flourish.

When approaching an algae problem it is important to recognize the difference between and algae bloom that is caused by an abundance of one of the three parameters mentioned here and the normal growing cycle of algae. Being a plant, algae will have a specific growing season in which it will temporarily bloom more than normal. There are countless different types of algae, all of which have there own unique properties, including their own unique growing seasons. Meaning if your algae is blooming in the fall don’t immediately assume it’s something other than it’s growing season just because it’s not happening in the spring or summer when most plants experience their growing season.

Of the three components algae requires to grow, water, light, and food, there is one that is much easier for the pond keeper to control than the others, food. Obviously it is difficult in most ponds to control the amount of water or light that is available for algae; but, food is different. The amount of food that is available for algae can be much more easily controlled by monitoring the nutrient levels within your water. Control the amount of nutrients algae has to feed on and you can directly control the amount of algae you have within your pond. Sounds simple, right? Unfortunately, the methods of controlling nutrient load include limiting the amount of fish in your pond, limiting how often and how much you feed them, growing specific macro algae and water plants to out compete the algae for the nutrients, and several other methods which result in limiting your enjoyment of your pond as well. That makes it necessary to develop additional ways of controlling algae which allow us to keep the fish and plants that we want in our ponds. Below you will find many of these methods.

Physical methods for reducing algae

This method for algae reduction is mainly used to deal with the results of an algae bloom. It does not address the cause of the algae bloom. Physical removal of algae can be a painstaking task but under the right circumstances it can be a great benefit. It is my belief that for most algae problems you should determine the cause of the algae bloom and address that before considering physical removal. That said, once the cause of the algae bloom has been addressed it tends to be very beneficial to follow that up with the physical removal of the existing algae. Compare your algae bloom to an ant problem. If you walk into your home and find a bunch of ants there are several courses of action you can take. Option one being killing all the ants you see, physical removal; but, you know they will return because the source of the problem still remains. Option two being finding the source of the ant problem, the bag of cookies you left out, and remove it; but, now you are still left with a bunch of ants running around and it takes time for them to leave. So what do we typically do when we have an ant problem; both. Most of us would throw the cookies in the trash and then kill the ants we can see. That’s how we should approach our algae problems. Find the source of the problem, the bag of cookies, remove it, and then physically remove the remaining algae. There are many products out today that will assist you in making the physical removal of your algae as painless as possible; but, none the less it’s still a labor intensive task. As you can see now, physical removal of algae can be a very important step in reducing your algae problems but it should not be the only step you make.

Chemical methods for reducing algae

Chemical additives used to control algae target the source(s) of your algae problem(s). Most of these chemicals or additives are simple and easy to use. With most of them you just open the bottle, dose your pond with the recommended dose, repeat per the instructions on the bottle, and enjoy the results. Sounds real simple; doesn’t it? Unfortunately, the downfall to chemical control is that the chemicals are very target specific. You need to know your source. Is your source phosphates, nutrients, pH imbalance, or one of the other hundreds of possibilities? There happens to be a different chemical for each one of those sources. Can you guess what happens if you use the wrong chemical for the wrong source? You guessed it; nothing! Or worst yet in could further complicate your problem. Chemical algae control is very effective and I highly recommend it; but, do your homework. Narrow down your possible sources and make an informed decision on which product to use depending upon your specific source. If you have difficulty narrowing your possible sources down then experiment with some of the broader additives that are less target specific, especially the natural ones such as barley bails. These products will not produce as dramatic of results as target specific additives will; but, they will get the job done and with less risk to your pond.

Filtration methods for reducing algae

In today’s pond market there are almost as many filters claiming to reduce algae as there are types of algae that need to be reduced. Some of these filters work extremely well for reducing or even eliminating algae problems and others hardly make a noticeable difference. So how can you tell which is which; by educating yourself. You should first educate yourself on your pond. Things you will want to consider include your pond volume, your biological load and the estimated source of your algae. These parameters will help you decide what type of filter you should be looking at as well as what size filter to consider. Next, give yourself an education on the available brands offering the type of filter you decide to look into. Talk to fellow hobbyist and get there first hand experiences with different brands. Read product reviews on the filter type you are looking for. The more you know about the available brands the better. Below you will find some of the more effective types of filters used for algae control and what sources they should be used on.

UV Sterilizers

Ultraviolet Sterilizers or UV Sterilizers are a very popular method of algae control. They also tend to be a very effective means of algae control when used appropriately. The concept of UV sterilization is very simple even though the science behind them is very complex. Simply put, algae is controlled by passing it by a very intense source of UV light. The radiation from the UV light penetrates the cell wall of the algae and either kills it or at a minimum it sterilizes the reproductive ability of the algae, hence the name UV Sterilizer. It is important to note that a UV filter will have the same affect on all microscopic life that passes though it, including parasites. Another added benefit to this filter; algae control and disease prevention in one unit. Now here’s the catch, the algae is exposed to the UV light/radiation by passing through the filter. This means the algae has to be free floating in the water, carried through the filter by a flow of water and remain in contact with the UV radiation long enough to be affected by it. A UV sterilizer can’t kill what isn’t exposed to it, like all that algae on your rocks, your waterfall, your filter box, etc. nor can it kill algae that does not remain in contact with it long enough for it to do it’s job. All these things need to be taken into account when you are considering the addition of a UV Sterilizer. I highly recommend that you read and adhere to the manufactures suggested flow rate for the sterilizer. If anything go lower on the flow rate but never exceed it. Also take a look at the UV sterilizer itself. Check out its design and get a feel for the contact time that the algae will have inside the unit. There is no set rule for this but I highly believe in common sense. If the distance between the input and the output seems short than it’s reasonable to assume the contact time will be minimal, especially when combined with unusually high flow rates. Please keep in mind that we are speaking in general terms. There are some very advanced UV sterilizer units on the market today that can boast compact size and high flow rates through advanced design; but, they are not the normal and expect to pay more for these units. All in all it is wise to research before you buy and take into account as many variables as you can including, but not limited, to size, design, and cost.  This type of filtration can be amazingly effective on floating and suspended algae forms as well be an effective method of significantly slowing the growth rate of other algae forms in your system.

Mechanical Filtration

The term mechanical filter covers a very broad spectrum of different devices used in ponds to remove suspended debris from the water. They come in countless types, forms, and styles. One thing most of these filters do have in common is some type of media or strainer that is used to collect the debris from the water. These types of media will vary in size depending upon what the size of its targeted debris is. To my knowledge there is no mechanical filter or mechanical filter media that is effective in the removal of algae. Yes, some types of media will remove some algae that get’s trapped within it; but, this is far from an effective means of filtering algae. That said, you are probably wondering why we have included a mechanical filter as a method of reducing algae. For that answer we need to look at the specific source of many algae problems, nutrients. Nutrients that are dissolved or suspended in the water are like a floating buffet for algae to feed upon. Now you might be asking yourself, if the algae is too small for a mechanical filter to remove than how is it possible to remove its food source? Wouldn’t its food source be smaller than it is? The answer is not as simple as you might think. Yes, in its usable form for algae the nutrients are much too small for a mechanical filter to remove; but who said the nutrients were always that small. When people first consider a high level of dissolved nutrients as being a likely source of their algae problem they look to the obvious nutrient sources first such as overfeeding and overstocking but often overlook the less obvious sources. Sources that are not intentionally added by the pond keeper but none the less enter the pond everyday. Things like leaves, bird droppings, bugs, etc. All these things add additional nutrients into your system and when left alone breakdown into small difficult to remove particles that algae loves to feed upon. This is where mechanical filtration can make a significant difference in controlling algae. Not by directly affecting the algae but by indirectly removing these larger sources of added nutrients before they have a chance to break down into a form usable by algae. It’s a lot easier to remove a leaf from a pond that it is to extract a leaves worth of dissolved nutrients from the water.

Where have my fish disappeared to?

Don’t panic. It is a common occurrence, especially for new pond keepers, to believe their fish have disappeared. Despite some people’s beliefs, there is always a reasonable explanation for where your fish have gone. And be rest assured many times the fish can be found alive and healthy, more often that not this problem occurs from a lack of understanding of fish behavior. Unfortunately, in some cases it’s the work of predators. This section has been designed to help you understand basic fish behavior so you know when to be alarmed and when not to be.

Understanding fish behavior

Even though fish are assumed to be very simple creatures that does not exclude them from having behavior patterns. Most of these behavior patterns are not complex or difficult to understand if you can put yourself in the fishes place; but, if you think of it like a person than they might seem a little silly. Fish can adopt several types of behaviors including ones derived from natural instinct or even learned behaviors from their experiences or from training, Yes, I said training. It is possible to train fish; but, we’ll save that specific topic for a different discussion. The particular fish behavior we are interested in for this discussion is survival. Fish have a very high will to survive. This can be seen anytime you remove a fish from water. It will flop around non stop continually trying to get back into the water all the way up to its last breath. I’ve never seen a fish just sit there and give up once it’s removed from the water. Have you? Its simple fish are survivors. To bad nature played a cruel joke on them and put them towards the bottom of the food chain with minimal ways of defending themselves. So if you are a creature with an extremely high will to survive but no way to defend your self then what do you do? The obvious answer is, hide. You become an expert at hiding, always knowing when and where to hide when danger is near. Chances are if you don’t see your fish, especially if it’s a new pond or a new fish that has been added to an old pond, that’s because it’s hiding. And it’s probably hiding from you. Your fish don’t realize that it was you who built this expensive little play area for them. To a fish you are a giant predator standing on the edge of the pond waiting to pounce on them and eat them. Same goes for a new fish added to an existing pond. Fish can’t talk. That fish has no way of finding out from the other fish in the pond that you are a good guy. That you are not going to eat him or her. That takes time to learn, a learned behavior for the fish. In time they will realize that you are not so bad and that you’re the food bringer. Fish quickly learn to appreciate the food bringer. But it doesn’t happen overnight. The more time you spend near your pond, without disturbing it, the quicker the fish will learn you are not a threat and come out of hiding more and more. This holds true for fish of all sizes. Even that ten pound koi you put in your pond yesterday but can’t seem to find this morning. Have you checked under or behind your waterfall where the water is all turbulent and you can’t see into? Fish are excellent at concealing themselves. Even once your fish begin to accept you as being friendly they may still hide quite often, especially in the early evening through the early morning times. This is primarily natural instinct to avoid predators during prime feeding time which is a behavior you want to see in your fish. Most ponds are very exposed typically being in an outdoor setting. Predators are a real threat to your fish and they know that. So they continue to hide. They continue to survive.

Predators

Predators come in many shapes and sizes which makes it difficult to protect a pond from all of them. For that reason it is good to know your opponent. Depending upon where you live that opponent or opponents will vary. Some of the most common predators that frequent ponds include herons, egrets, raccoons, hawks, and owls. It’s a given fact that if you have a pond that contains fish and is exposed to the outdoors sooner or later you will have a predator visit your pond. It is best to be prepared rather than losing the majority of your fish from the first attack. There are many methods to discourage predators but unfortunately that’s exactly what they do, discourage them. Rarely will you completely eliminate a predator problem. At best you usually discourage them and reduce the frequency in which they come around and reduce the damage they inflict when they do come. There are several methods used for protecting a pond but three main concepts are used most often either individually or in combination together. The first is pond netting. This methods utilizes a thick mesh net which is placed over the surface of the pond water and securely staked all around the ponds edge. This method can be very effective in preventing predators from being successful in removing your fish. Unfortunately, though it does not stop them from trying. Which means you can end up with injured fish rather than missing fish. It also tends to take away from the beauty of your pond. The second popular method is decoys. This method uses artificial decoys which look like the predators of the predators you are trying to discourage or in some cases decoys which look like the predators that you want to discourage. Many predators are very territorial. So by placing a Great Blue Heron Decoy next to your pond you might be successful in reducing the frequency in which you get a real Great Blue Heron visiting your pond. There are several types of decoys available today, each used for a specific purpose. Do your research on the predator you are dealing with and do your research on the decoy you are interested in. It is important to note that predators are inelegant creatures and in many cases it does not take long for a predator to realize when a decoy is artificial.  The final method for controlling predators that we are going to discuss is my personal favorite. It consists of a motion activated sprinkle that you place at your ponds edge. This sprinkler is connected to a garden hose and stands guard over your pond all day every day. When a predator, or anything for that matter, makes a move within the range of its motion sensor it blasts them with a stream of water. This method can be very effective in scaring predators away; but, it can also scare other things away to. Kids, friends, neighbors, or anyone who either forgot it’s there or never knew it was there will get an unexpected shower. It would be my personal recommendation to consider implementing as many of these predator control means as possible at the same time. The better protected your pond the more enjoyment you can get out of it without breaking your pocketbook in replacement cost of livestock.