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Pond Supplies

Our Pond Solutions Newsletter


Small Pond Algae Control - Kill Pond Algae

Algae control for ponds less than 50' x 50' in size.

Answers to the infamous question...

How Do I Get Rid of My Pond Algae?

First of all, there's primarily 2 types of algae that plagues most people's ornamental ponds; string algae and the notorious plankton algae that makes your pond water green like a "lovely" bowl of split pea soup (yuck).   Both types of algae grow by somewhat different methods, so I will explain each one of them to you individually.

String algae is pretty simple.  It usually grows along the bottom or edges of your pond where there isn't a lot of water circulation.  It looks like a bunch of green hair and looks pretty awful, too.   To kill string algae you need to remove the water from your pond or waterfall (ideal time to do that is during spring cleaning) and liberally sprinkle Kosher Salt on it. ( It must be Kosher Salt or non-iodized salt and NOT table salt).  Let it sit for at least 3 days and then brush off and rinse and clean the pond thoroughly.  There CANNOT be any fish in the pond during this time, so the choice is yours and if you are set up to remove your fish and if it's worth the hassle. You can also use our Green Clean to kill the string algae without emptying the pond.  You can find out about it here

Plankton, our lovely "pea soup" algae is probably the most common type of algae in ponds and lakes.  It's the stuff that makes the water look green and causes you to not be able to see your wonderful fish.  The best way to explain how to get rid of planktonic algae is to first understand what causes it to grow.

Plankton requires primarily 2 things to grow: sunlight and nutrition.  The sunlight obviously comes from the sun and the nutrition comes from biproducts from fish waste, dead and decaying leaves, decomposed fish food (make sure you don't over feed your fish) decaying aquatic plants and weeds, and nearby chemicals and fertilizers that filter into the pond. (Particularly if your pond sits in a lower part of your yard).  Most ponds I've seen have at least some, if not all of the above nutrients in their pond. (And have green water, too!)  The way to get rid of or reduce the amount of algae in your pond is by reducing the amount of sunlight and nutrients available to it.

Sunlight can be reduced by providing shade to your pond either above or by adding aquatic plants such as water lilies or other floating plants including water hyacinths.  The leaves of these plants help to cover the surface area of your pond and also make the pond look pretty. You can also use an aquatic "sun blocker" such as Aquashade, Black Vail, etc..  Nutrients on the other hand, can be reduced in a couple of different ways.

To reduce the nutrients in your pond which is causing your algae to thrive, you first need to clean your pond.  Get rid of any dead and decaying leaves on the bottom or along the sides of the pond.  Once you have that done, get a skimmer so you can have leaves and debris that may blow into your pond get sucked up before they ever settle and start to decompose. If you don't want to get a skimmer, get a Pond Net (you also can keep out predators such as raccoons, blue herons, cats, etc. with a net) or make it a practice to clean the debris off the pond every day or so.  If you need help at getting the leaves out of the bottom of your pond, get a Pond Vacuum that will help remove them.

The next way to get rid of the nutrients in your pond is by adding beneficial bacteria to your pond. You see, there are 2 types of bacteria;  the "bad" kind of bacteria and the good kind!   Bad types of bacteria can cause a lot of problems to your fish's health and can be pretty involved to explain.  To keep it simple, these bad types of bacteria can eat away at their skin, their gills, and cause them to be sick and die.  Needless to say, you don't want the "bad" type of bacteria.  The good, or "beneficial" bacteria is a type of bacteria that is required to not only break down toxic ammonia from fish wastes into harmless nitrates (referred to as the Nitrogen Cycle - which is something you want in your pond) but they also consume the same nutrients as algae does!  So, when you add more beneficial bacteria, you starve out the algae, thus resulting in a clearer pond!  Beneficial bacteria also breaks down sludge build up, "muck" on the bottom of koi ponds and fish ponds and much more.  It is absolutely vital to having any healthy pond.  So what do you need to do to establish some beneficial bacteria in your pond?  Provide them a place to grow such as a biological filter, rocks, plants, and filter media.  Establishing a nice colony of beneficial bacteria can take 3-8 weeks but you can actually get a "jump start" on things by adding some beneficial bacteria to you pond.  The best product we've used is an all-natural product called Microbe Lift.   It works great (we use it on our own small ponds and water gardens) and it can be used throughout the season as a good maintenance plan to keep your pond clear.   We also recommend our PlanktoniX Pond Bacteria beneficial for large fish ponds over 50' x 50' in size all the way up to lakes several acres in size!

I do have to mention some other products that are out on the market (and yes, even on our website) that will "destroy" algae, but these products will only work for a short time.  They are a temporary solution.  How they are supposed to work is by killing the algae and then the dead algae is supposed to be filtered through your filter.  What essentially happens is that the dead algae builds up on the bottom of the pond and creates an organic "compost pile".   This provides tons of nutrients and causes more algae to bloom in a couple of weeks.  People who continually use these products are actually making the algae situation worse.  You're continually providing more and more food the very algae that you're trying to get rid of!  It creates a vicious cycle and you need to stop the cycle.  By continually adding these chemicals & algaecides to your pond, you're changing the pond's chemistry and ecological system.  You need to add beneficial bacteria to the pond to reduce the nutrients available to the algae.  This will eventually starve out the algae and stop the cycle and result in a clearer, healthier pond.

Now, since I have your attention :o), I'd like to address Spring Care (can be applied for Fall Care too) for your pond and all the many wonderful questions we answer about Spring Cleaning...

Spring Cleaning....oh how wonderful it is!  We, who hibernate during the winter are all anxious to start cleaning out our pond once the weather turns warm and we're disgusted when the water is so darn green that you can't see your fish or anything else.  Sometimes there's a "fishy" or nasty smell, too.  Well, put on your gloves and let's get to work!

The first thing you can do to clean your pond is get out the nasty debris that fell in it during the fall and winter.  All the mucky leaves and things you don't even recognize! :o(  Naturally if you had a skimmer or a net, you wouldn't have all this debris in there, but you can't say I didn't tell you so!  :o)

It's best to empty the pond and clean it good with plain o'l tap water. ( You can put your fish in a container with a small aerator while cleaning.)  Be sure to get out the leaves and muck that seemed to have found it's way to your pond.  If you can't clean it out all the way (the more you clean it out the better off the pond will be) do at least a 50% water change.   This gets rid of some of the nutrients and any other junk that's in your pond.  Stir things up a bit while you're emptying it to get out as much debris as you can.  Be sure that your pump will handle the muck and debris and check often for the pump getting clogged up.   If you decide to do the partial water change you won't necessarily need to take your fish out to do this, but if you can, that would be great so you can see how your fish have survived and if they have any wounds or anchor worm or anything else that need to be treated.  If you really need to, you can do another partial water change in another week.  Be sure to run the tap water through some Activated Filter Carbon  which neutralizes the toxic chlorine and chloramine out of the tap water.  You can also add Ammo Lock 2 instead which will neutralize the chlorine and chloramine in the tap water.  If you have a bad case of string algae, you can clean the entire pond as I described above and then "start over" with filling your pond. 

One thing I want to mention is that EVERY pond in the Spring has a big algae bloom.  This is only natural and I know that it is so discouraging and disgusting to most of you.  After a long Winter we're so eager to see our fish and we can't because the water is like pea soup!  Part of this is due to the change in the temperature outside.  This happens because the beneficial bacteria hasn't started to grow yet and the pond is FULL of nutrients from dead, decaying leaves and debris from the winter.  Now the algae has the upper hand and is continuing to thrive.  What you need to do is add some of the Microbe Lift/Autumn Prep (for small backyard ponds, water gardens, koi ponds and any pond less than 50' x 50' in size) and be PATIENT. Add your aerator, turn your pump and waterfall on or whatever water feature you have and after 2-3 days add the Microbe Lift.  Remember, what you're doing is creating an 'ecological system' and this isn't a 'quick fix'.  Whatever you do, don't get discouraged and periodically empty part of your pond.  What you're doing each time you add tap water to your pond is KILLING THE BENEFICIAL BACTERIA.  That is why you just have to leave it alone.  Get your pump and filter going.  Have you aerator on and be patient.  Time and Microbe Lift (for small backyard ponds, koi ponds and water gardens) will take care of it.  You will definitely see improvements within 2-3 weeks and continue to see improvements thereafter.  Use the Microbe Lift too, as a maintenance to reduce the algae and keep your pond clearer.  (Use the PlanktoniX for large fish ponds and lakes over 50' x 50' in size.)

One other thing that I would like to mention (since we are frequently asked this) is "what can I do about the algae in shallow areas of my pond?".  Well, that one is a toughy and nothing is really going to help it much besides trying to increase the circulation to those areas.  You see, the water in the shallow areas (around 6" or so) gets really warm and since there is less circulation because it is so shallow, well, that only causes more algae to grow.  This is a different kind of algae and is going to pretty much cling to the rocks or anything else you have there.  I guess the best thing to "fix" this is to create your pond so it doesn't have a real shallow edge in order to avoid this.  If it's not avoidable, then trying to increase the circulation is the next best thing besides raking out any debris that collects in this area.

Speaking of circulation, I will remind you that in order to have proper circulation in your pond, you want your pump to pump at least 1/2 the total volume of your pond every hour and have a filter that will filter the total volume of your pond at least every 3-4 hours.  If you have your pond in full sun, then opt for a larger filter.  The filtration system for your pond is probably the most important part of your pond.  Always go with a larger filter than what is 'recommended'.    A huge portion of people new to ponds and water gardens over-populate their pond with too many fish which put more demands on the filtration system and then have all kinds of problems with green water, etc.  Be smart and put your money and thought into the filtration system and you'll be glad you did.

Well, there you have it;  some suggestions at maintaining a healthy, clearer and more enjoyable pond.  I hope this information helps you!  Don't forget we have a Build a Pond ebook course that explains how to create a pond, how to determine your pump and filter sizes and much more.  Take a look at it.  We also have free information throughout out site about fish care, a safe amount of fish you can have in your pond and how to properly transfer fish to your pond.  I'm sure you will find this information invaluable.  

For those of you who have very large ponds and lakes, please check out our information for controlling algae and pond weeds in lakes (the way to treat ponds and lakes over 50' x 50' in size is different than the treatment for small backyard ponds and water gardens since obviously the volume of water and size of area are substantially different.)

We at PondSolutions.com are happy to help you.  Please contact us with any questions you may have.