Pond Algae

We aren’t quite into the heart of fall but it’s soon coming, and along with that, the leaves will begin to swish and sway towards the ground.

And let’s be honest. A pond is basically a hole in the ground with water in it.

Which means that if your pond lies beneath an overhanging tree, a leaf or two (or maybe countless more) will drop into the pond.

The problem is, you don’t really want this if your main goal is to keep a pond clear of algae and other problems.

Small Pond Folks Have A Few Viable Options

Small pond owners are fortunate in one sense. You have quite a few options.

You could have a skimmer installed to collect many of the leaves.

You could cover the pond with a net and stop most of them.

Or you might shut the pond down altogether as you get into early winter. Just drain the water, clean out the basin, and wait for next spring.

Or if you’re going to keep it open, removing leaves and debris isn’t too bad with a good pond vacuum and some sweat equity.

The thing you don’t want to do is let them sit at the bottom and rot away.

All those leaves and other organic debris will eventually turn to a beautiful, black, maybe stinky, nutrient rich muck.

And there’s no better way to grow algae.

For large pond owners, things aren’t quite so simple.

Normally you won’t be emptying the water out to clean the bottom.

A pond vacuum isn’t going to work here. And netting, well, it’s not very practical. A skimmer…sorry, no can do.

So, without a doubt, leaves and debris will surely sink to the bottom and stay there.

Limit Muck Build Up And Enjoy A Healthier Pond

For bigger ponds, the best remedy to limit muck build up, is to stop it before it really starts to become an issue.

With fresh leaves and other organic things…and this includes algae and weeds that are either killed off, or die off just due to the cooler weather, my goal is to break these suckers down as fast as possible.

Then naturally occurring bacteria can readily take care of the rest.

Enzymes Are The Key

In nature, the initial stages of breakdown are created by enzymes.

Enzymes are kind of like saliva for us humans.

They prepare the digestible parts of the plant for further consumption, either by our tummy and such, or in the case of a pond, by the beneficial microbes that reside there.

The main point is that enzymes are a critical part of the digestive cycle, and in a pond, if this material isn’t broken down quickly, muck will usually develop and it’s harder (meaning it takes longer) to get rid of than just a simple freshly departed plant.

What we’ve found in recent years, is by adding some specific enzyme catalysts we can limit muck build up quite a bit.

We use PondBiotix MDC for this and we add it right after any kind of treatment that might kill algae, duckweed, or other aquatic weeds.

Or we add it in the fall, after any existing plant life has died off naturally.

Following this, if we haven’t been using it much up to this point, we might add some good beneficial bacteria to the pond to help with the continue breakdown and assimilation of the dead plants.

MDC is too concentrated for small ponds but we also will use good bacteria here and it will go along way, in combination with some of the other things noted above, to clean a small pond up nicely.

And finally, what’s a pond owner to do if they miss this early stage of muck development and end up with the black stuff sitting on the bottom?

Since this type of muck is well established the best route to go is to use a specific bacteria in pellet form called PondBiotix ME, which sinks into the muck and degrades it away gradually.

Usually within a month you’ll see some good progress on the buildup, but there’s one thing to note. This type of bacteria works best in warmer water.

MDC however can be used in any temperature.

As I almost always point out, good bacteria, and most everything else you add to a pond, will work better when there’s good aeration going, and it will also protect fish during the die off phase of any plants in the pond.

Got any other questions about muck reduction in your pond? Share those below!

A recent article from a Sauk Valley newspaper discussed the ongoing algae problems in a community park pond. I wouldn’t say though that the story came out with a happy ending.

There are several notable steps the city took to help work against the algae issues and most were pretty good to start with. Let’s cover those first.

Since the pond had a lot of sediment build up in it, and it was a good bet this stuff was pretty nutrient rich, they dredged the pond and removed much of this organic debris. If you can do this, and make note that this is much easier in a small pond, then it’s a good step to take. Muck reducing bacteria can help here too but it won’t be as fast as dredging.

In addition, they took steps to hire a landscaper and pruned some of the trees that overhang around the pond. This is a proactive step to at least lessen the amount of leaf debris that can fall into the pond. And they are working to create some grass buffer strips around the pond to help with run off. For a larger pond like this, both of these issues (leaves and run off) represent the major influences that affect nutrients in the water.

And finally, a fountain was added to the pond to help aerate and circulate the water. This is a very powerful and important step because stagnant water is highly prone to algae and other problems. Adding oxygen to the water is the best way to stimulate naturally occurring microbes that will help keep the pond cleaner.

Before going further, let’s always remember that nutrients directly affect algae growth. The higher the nutrients, the more algae you’ll usually get.

When you think of an algae problem like this, it makes sense to do all of the things that were noted above. The city was wise to take these steps.

But then the algae came back quickly.

This isn’t an unusual thing.  

You see it in ponds all the time.  A small pond owner cleans out everything, vacuums all the muck out, fills the pond again with water, and in days, algae starts coming back.

This big pond wasn’t really all that different.

What must happen after all this clean up work is done?

Well, first you have set the stage for a much cleaner pond overall, but one element remains missing.  You still want to either allow naturally occurring beneficial bacteria to repopulate the pond, or you’ll want to add it to the pond yourself to help jump start things.

These little microbes have to build up in enough density and number to begin to outcompete algae for any nutrients that remain in the water.   And when they reach a certain point in number, then algae will often begin to regress or disappear, simply because the available nutrients are going down.

But rather than add good microbes to the pond to help keep the pond cleaner, the city was guided to do something completely different.

They killed the floating algae with copper sulphate.

Now granted, they no doubt wanted a quick fix, and that’s understandable.  Certain folks probably had to justify getting that fountain and dredging all done and there’s an expense to that, and well, it doesn’t look so good when algae comes back so fast.

But if they understood why it was blooming so well, and that in the very early stages, it can grow back faster than bacteria can get established, then they would know that using an algaecide, and particularly copper sulphate isn’t the best way to go forward.  

You see, those copper based chemicals actually kill good bacteria right along with the algae, so in effect, they are sterilizing and removing the only thing that could help keep the pond cleaner, and lower in organic build up.  

It’s a shame really, because they’ll be dredging again in just a few years if they keep this up.

But this city isn’t alone.  This old “tried and true” method of algae control us still used widely by a lot of folks.  

That doesn’t make it sensible, however.

In my mind, algaecides should be held back as the last resort IF YOU HAVE TO USE THEM, and in most cases you don’t.  If someone tells you otherwise, they haven’t witnessed the results we have over the last 10 years…most likely because they remain stuck in an old way of thinking.  And that is the chemicals are the only answer to an algae problem.

Simply stated, they are not.

So the moral of this story is that you can do a lot of things right when it comes to pond algae control, and still make a bad decision here and there, that could make it a lot harder to keep a pond clean than it has to be.

To learn about our standard protocol for dealing with algae problems in small ponds, visit this page.  And for large ponds, you can click here for more information.

Pond algae needs certain things to grow really well. It’s a plant after all, and if you ask any good gardner what they like to see come growing season, it’s a nice balance of sun, rain, and some really good, nutrient rich soil.

For a pond owner, that “soil” might be at the bottom of the pond, or when it comes to nutrients in general, they could even wash into the pond in various ways. However they get in there though, the focus needs to be on reducing or managing these nutrients to keep algae in check.

Whenever you hear of someone having success on algae blooms, without using some kind of killing tool like an algaecide, you can bet that what really happened is that somehow, some way, the nutrients were simply made unavailable for algae to use to grow well.

While there are a number of nutrients in pond water, the one that probably has the most influence on algae is called phosphorus. Some experts have noted that for every pound of phosphate in a pond, 500 pounds of algae can be produced! So that’s quite a stimulant.

Phosphorus is a key element in nature though and it really is a beneficial thing to life on earth. It’s just that too much, in the wrong place (like your pond) can be a problem.

Where Phosphates Come From

Phosphates can come from a lot of places but the most common sources are, well, quite common.

If you live in agricultural lands, then fertilizers containing phosphorus are used frequently. Runoff following rainy days, can go directly into the pond or via source water from incoming streams and spike the nutrient in a pond. Leaves, as they decay, can give off phosphorus, as does the waste material from waterfowl like geese and ducks.

If you feed your fish, many commercial fish formulas contain phosphorus (some of it is quite healthy for fish) but if a lot of the food goes uneaten, it would be added directly to the water.

Phosphorus Isn’t All Bad

It’s important to not give the impression that phosphorus or phosphates are all necessarily bad things. They aren’t. As mentioned before, the nutrient is critical to healthy life on earth. Plants benefit from it greatly, as does every living thing. Without it we’d be in a world of hurt.

But it’s critical to remember that algae and other aquatic weeds use it for rapid and expansive growth so if you’ve got an ongoing, hard to control, weed or algae problem, then phosphorus really should be analyzed. If the readings are fairly high then it makes sense to do something about it.

The funny thing is, it’s not really accurate to say that phosphates were reduced in a pond. They don’t go anywhere really. But the most effective way to reduce their effects, is to bind to them with something that makes them unavailable as a food source for algae.

Aluminum Sulphate Binds To Phosphorus

One of the most common binders that you’ll see marketed today is called Alum, or Aluminum Sulphate. It’s an excellent chemical phosphate binder. But one precaution related to Alum is that it’s very acidic and it can drop the pH of the pond water very quickly in some instances. It’s for this reason that I’d suggest avoiding the use of unbuffered Alum. Buffered formulas that include Alum along with Sodium Bicarbonate will help to offset some of the effects on pH.

Some specialized formulas use polymers along with lower doses of Alum and these have much better stability in terms of how they affect pH. Then there’s another, all natural, calcium based solution which is completely organic and won’t affect pH at all. Currently we prefer this formula over the others. It works more slowly but is an effective tool for taking the available phosphates away from the ravenous algae cells that love them so much!

And what about dosage rates. Well, from product to product you’ll find some variability here. Follow the suggested label directions and dosing of whatever you’re using. Remember though that these rates will vary a lot based on the amount of phosphorus in your pond water. Higher doses of any binder will be required for high levels of phosphate. In most cases you can add repeated doses as needed while checking phosphate levels as you go. The goal should be to keep them down around 10 to 30 ppm or less.

Click here to view our complete line of phosphate binding products.