Don't be fooled. Inside this thin coating of sweetness is a fiery core of total insanity.

Wednesday, June 6, 2012

How I Got Rid of the String Algae in My Stream

You probably won't like my solution to getting rid of string algae. It's simple, but effective. But it's also hard work. It involves using a tool that every gardener has, that costs nothing and can't be bought at a store. No nasty chemicals either.

First, here's a picture of what my stream looked like after I turned the pump off.


My solution doesn't involve using chemicals to kill the algae, it involves simply getting in there on my hands and knees and rolling that string algae up, like a blanket. I actually turned the water off a couple of days ago, and waited for all the water to drain out of the stream and down into the reservoir.

Peeling it off the rocks is not all that difficult, it's just time-consuming and meticulous work. Sometimes it peels off fairly easily, but sometimes it clings quite tenaciously to the rocks, especially the little ones. And I had to be ready for encounters with every critter that loves moist, decaying plant material. There were all manner of slugs, snails, roly-poly bugs and even centipedes and earthworms in there.

I do this work with latex gloves on, and knee pads. Crawling around on those rocks is not comfortable on my legs, otherwise.

Eventually I do end up with a relatively cleaner stream.

There are still a few rocks with tendrils of string algae stuck on them. It is physically impossible to remove all of it.

My final step is to get down on my hands and knees once more, with a bin full of hydrogen peroxide and a scrub brush. I don't scrub them clean, but my goal is to get some of that hydrogen peroxide onto as much of those left-over clinging bits and pieces as possible.

I have tried using chemicals in the past to kill the string algae. It turns the algae white for a few days, and then it turns green again, and comes roaring back to life as bad as ever, if not worse. I've done some research online, and it turns out that the algae that the chemicals kills actually provides fertilizer for a whole new generation. So by killing it and not removing it you are actually feeding it. Kind of like side dressing your weeds with compost.

I've come to realize that rolling up the string algae physically and removing it like this is really just another form of weeding. Instead of weeding my garden bed, I am weeding the stream.

Oh, are you ready to see the costs-nothing, can't buy it a store tool that every gardener has? Here it is.

Lucky me, I have two of them.


  1. You need to patent this method, Alison! Your stream looks wonderful now!

  2. Yup, often it is a case of getting in and getting your hands dirty. A thing most gardeners don't seem to mind!

  3. Ha ha ha! We had that same nasty stuff too when we had fish..Now our pond is empty and ready to be moved. I would take different tools to fish some of it out but as you know it never really helped. I can see that your method is the only way.

    Do you love how the chemical stuff feeds the next about job security for the manufacturer!

    If you don't have any other plants in there, you could use straight will kill all green things and you wouldn't have to scrub. Be careful not to get it anywhere near any plant that you love. xo

  4. Sting algae looks pretty nasty -- hope you can figure out how to permanently get rid of it.

  5. Yuck! But as usual it's all about the labor way to "just to it"...

  6. Wow! it looks fabulous. I think your solution was the best because killing it would still require you to clean it up. Your solution was actually a time saver.

  7. Wow--great work, Alison! I don't use chemicals in our stream either--but we don't have any problems with string algae. I wonder why? The stream gets both sun and shade. I do sprinkle in (about every couple of weeks) some powdered 'Beneficial Bacteria' by Aquascape--a non-toxic formulation to keep the stream clear. I don't use any of their other cleaners though as they are all toxic. I also have a bag of Barley placed under a heavy rock in the top in the 'well'...barley is excellent for keeping the water clean and clear. If you don't use either of those I highly recommend them. I have NO cleaning to do in mine other than picking out leaves, branches, the Tulips that fall from the tulip poplar trees, and maybe every couple of years having the company that installed the stream come and suction out the recirculating boxes where debris has settled.

  8. Oh--and I keep a ton of water-stream-pond plants in pots in the stream. I surround the pots with rocks so they stay in place and leave them there all winter long and the plants stay contained and have come back this year. That helps with the excess nitrogen levels from debris...

  9. Good for you for sparing the chemicals. I'm amazed at the ease in which folks pour toxic chemicals around their property. I'm doing some research on food-grade hydrogen peroxide, which one friend uses in her fountain on occasion. Apparently it's not harmful to fauna but changes pH for aglae. Still looking into this.

  10. Yep. I've got two too! And I also use mine to extract that slimy string from my pond waters. The nice thing is that it only "blooms" in the spring and fall. Once you take care of it in the spring, you're okay for awhile. I know there are nontoxic methods but it seems easier to just use the ole 5-finger method.


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