123) Pond issues

by Gail on May 9, 2011

My family and my other two blog followers are always badgering me (yes, badgering me, I tell you) to keep the posts coming. We’re well-occupied working on the house still, but this blog is called “This Green House”. To stay true to the theme of the blog, I feel it’s best to only post when I have something green to report.

Algae is green. There’s too much of it in our pond, especially the notorious string algae. scrubbing algae

When Endless Rain installed our rainwater collection system, we got a water feature built to take advantage of the many benefits of flowing water, not least of which is for flushing toilets and watering the garden. water feature

We ran the pump for our lovely waterfall June to December, until the plumbers came to do some toilet-flushing work and the electrician to install an outdoor plug for it. They left the pump off during the freezing weather, and the pipe to the pump burst. The water feature was turned off for 5 months, during which the 6″ deep top pond stayed full of water.

The plumbers came a couple of weeks ago, and hooked up the pump. After only a week of running waterfall, it became obvious we had an algae problem. Green slimy algae covered the rocks and obscured the pond bottom. Why did the algae bloom so fervently in one week, when there didn’t seem to be a problem for the first 6 months of the pond’s existence?

When Allan installed the system, he told me that pond plants would help keep the pond clean. In addition, because the water would be continuously flowing, there shouldn’t be an algae problem. After a bit of research, this is what I think has happened:

As it turns out, the water is only flowing on the surface of the pond. Below the surface, the water can be quite still. (Had I known then what I know now, I would not have had them build a pond at all, just a series of plateaux for the water to run over.) Shortly after the system was completed, I did buy a few water plants, and they flourished, particularly the water hyacinth, which was planted in the filter basin (to control its growth – It can take over like a bad weed.)

Biofalls Filter with dormant water plants

Biofalls Filter with dormant water plants

The water hyacinth is sprouting today

Over the winter all the plants died back, but water and organic material still collected in the pond. And, horror-of-horrors, the new garden, with its rich composted soil, was draining its dark, nutrient-rich water into the storage tank. So when the system was turned on again, the plants couldn’t do their job of using /filtering the nutrients that collected.  The goop fed the algae very nicely. It was happy. I was not.

I spent several hours today cleaning it out. We diverted the garden drainage so that it didn’t enter the system. I drained the pond into the “wild” with my neat new Lee Valley siphon pump. Then I took out as many rocks/gravel as I could, setting them out in the sun to bake away the algae.

Sun baking the algae-covered gravel

Sun baking the algae-covered gravel

I scrubbed all the boulders, rocks and gravel with a brush (and cloth in the tight spots), spraying them down with a water hose. There was still lots of sludge, so I pain-stakingly used my masonry sponge to sop up the dirt and wring it into a bucket.

Cleaned (top), sludge (bottom)

Cleaned (top), sludge (bottom)

Basin cleaned: just clean sand and a bit of gravel left to dry

Basin cleaned: just clean sand and a bit of gravel left to dry

The pond is drying out thoroughly before I put the gravel back and plant more water plants. I will also use a product called EcoBlast, which purports to add beneficial nutrients and enzymes and remove pond debris. I hope this does the trick, or it will be a running battle for the life of the water feature.

We’ll see if it returns to its former beauty. Will report.

Update, July 14: I was so optimistic when I wrote this post, but in fact, the algae came back and I had to do the whole cleaning routine again.This time, I used the shop vac (wet and dry vac) to vacuum up the gungy water.

I purchase more pond plants, mostly iris and water hyacinth. water hyacinth

And, I don’t know if this has helped, but I read that algae, like most plants, don’t like copper. I could throw a bunch of pennies into the pond, but I decided to try wrapping copper wire around a flat stone at the top of the waterfall, right after the biofalls filter. copper-wrapped stone

The danger is I could kill all the beneficial plants with it, too.

Whatever the reason, the water feature is behaving itself. It’s been running for about 5 weeks, through sunny and cloudy weather, and the water looks clear. cleaner pond

What a relief!

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