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.