How to rid canals of algae (Aquaculture)

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We're getting ready to move to a farm with a nice pond and canals. The canals are approx. 15'-20' wide and filled with stagnant icky green algae. There were (are?) muskrats living in them. Does anyone know of anything that can be put in them to help clean them? We are planning on dragging out some old tree limbs and debris that are in them but what about the other stuff? Gloria

-- Gloria Mullinax (mullinaxclan@webtv.net), April 22, 2001

Answers

Response to How to rid canals of algae

First of all, what type of algae is it? Is it a stringy type kind or is it duckweed? Duckweed is actually little florettes that float on the water and their roots hang down into the water. Duckweed is much harder to get rid of and reoccurs even after "ridding" it. To get rid of duckweed, you can use copper sulfate, but there are three drawbacks. It takes a lot of copper sulfate. You can't get rid of the copper sulfate after it is in the water or at the bottom. The duckweed will return.

Duckweed is very persistent. It has been said that ducks will eat duckweed and therefore keep it in check. I can not verify that.

About the only thing you can do with duckweed is manually skim it off. This is labor intensive and you have to keep doing it. Duckweed occurs in waters due to stagnation and high nutritional content. The high nutritional content can be due to sewage, fertilizer runoff or rotting weeds in the water. Make sure your pond gets plenty of sunshine, and air. Keep growth around it down. Open it up to the sunlight and the wind if there is heavy growth around it.

You might even consider adding a mechanical aerator if that is feasible. But even mechanical aerators have their limits. No growth will occur around them, while they are running, within a a few yards. One aerator on a large pond is not going to keep down duckweed on the entire pond.

For stringy type algae:

You can scrub the canals with a stiff brush to remove the worst parts of it.(This of course, is for small canals with a metal or wooden base.) Try small doses of chlorine bleach. You didn't mention where the canals led to. Chlorine in water is highly regulated by law. If all of this water is staying on your property and if you can stop up the canals for a period of time, so there is no water running out of them to another place where there might be fish life, then dose the canals with chlorine bleach. Let it sit for a day and then rinse the canals through. It may take more than one dosing to get rid of the algae.

But algae is always going to grow back. Keep the ponds and canals as clean as possible and this may help slow the growth. Algae is growing on the nutrients in the water.

I have heard that there is a blue dye that is available (swimming pool supplies?) that home pond owners use to prevent algae growth. Somehow it prevents the algae from receiving sunlight and therefore doesn't grow.

Therein lies an advantage with duckweed. It blocks sunlight into the water and prevents the stringy type algae from growing. So if anyone wants to grow duckweed, which is highly nutritional and is fed to cattle once it has dried, you can get a bucket of it from a pond and throw it into yours. It will take off like a weed!

-- R. (thor610@yahoo.com), April 23, 2001.


Response to How to rid canals of algae

I have no actual experience, but I did read something recently in a book on ponds: Crawfish. They will eat all the algae. But then you have lots of crawfish and you'll never get rid of them. Some people think this is a good thing. Some people think this is a bad thing.

-- Paul Wheaton (paul@javaranch.com), April 23, 2001.

I can't help you with how to get rid of it. However, if it's slimy stringy stuff then it's likely to be blue-green algae (which can actually be bluish green or a reddish brown or even bright green). This stuff can be highly poisonous. Try doing some Web searches on "blue-green algae". However, the big secret is that you don't want anything like that in your water. Even if it's not poisonous it can generate poisons if it rots in the water. As I said, search the web for answers, but a big part of the secret is to keep raking it out and piling it up (FREE compost!).

-- Don Armstrong (darmst@yahoo.com.au), April 23, 2001.

Thanks everyone for the suggestions. I don' know what kind of algae it is but it's worse where its the stillest. I don't know where it runs to and I believe it could have a lot of run off from the fields in it. To start with I think we'll clear ot the debris and rake out the other as much as possible. There is one place that goes under a small bridge and looks to be clogged. Thats where its the worse. I am thinking about getting some ducks or geese - maybe that would help?? Gloria

-- gloria mullinax (mullinaxclan@webtv.net), April 24, 2001.

You might want to take a sample in to your extension office to find out exactly what variety it is.

I don't think ducks and geese eat that stuff. I think snails would.

-- Paul Wheaton (paul@javaranch.com), April 26, 2001.



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