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.|