cleaning up a pond

[hoosier]

I made great progress on ours cleaning it by hand, but it was the drought that dried the pond and left fissures several inches deep that finally knocked the algae back completely. I then put five little pond plants I picked up hoping they would multiply and shade it. It turns out they are invasive and have they ever multiplied! Fortunately, there is no danger of them escaping our little pond.
Our large pond had a lot of algae - mostly around the edges - which I removed by hand. It was a lot of work over the course of a couple of years, but I was concerned about using chemicals as I didn't want to harm the frogs, toads, fish....
Good luck.

 

[k0xxx]

We have a long neglected pond at the new place that is pretty much covered with algae. What are the best ways to clear it out? DH tried doing it by hand, but didn't make much progress that way. People keep recommending copper sulfate, but I'm not sure what the ecological ramifications are on that. Suggestions?

Have you contacted your county agent? They have a lot of resources and can be very helpful with these types of problems. At the very least, the agent should be able to point you in the right direction. Ours was very helpful, although it was a problem of a different sort.

 

[Farmfresh]

How about a Barley Ball? Or a homemade version of the same with some barley grass or hay in a gunny sack? More info

 

[Wifezilla]

Go ahead and laugh DrakeMaiden. I still haven't checked to see if I have any fish left! Shelley is WAY too smart for a duck. The scary part is I have babies hatching and I am pretty sure some are hers. I think they are going to try and take over....

 

[curly_kate]

Have you contacted your county agent? They have a lot of resources and can be very helpful with these types of problems. At the very least, the agent should be able to point you in the right direction. Ours was very helpful, although it was a problem of a different sort.

We went to the extension first, and they are the ones who recommended the copper sulfate.

 

[patandchickens]

Copper sulfate is at best a temporary fix, and not a good one at that IMO, so I am glad you're not doing it

There are excess algae in your pond b/c there are excess dissolved nutrients in your pond. You can kill or filter out or hand-remove the algae but it'll just come right back as long as the same amount of nutrients are still present in the water.

If this is just a fairly thin "hairy" algal scum over the surface of the water, it may be fairly easy to fix. If however it is a seriously thick scum, or if there is little scum but the water is like pea soup, you probably have a serious nutrient overload and that can be real hard to deal with.

Plants help -- specifically, plants that take up nutrients from the water directly, not from their roots. But you have to be careful WHAT plants, because in a situation with excess nutrients THEY can often become a problem THEMSELVES.

I seriously don't recommend duckweed, it can totally blanket a pond and you will never, ever, ever get rid of it. (Yeah, it dies back in winter, but it will be back every summer. Really truly.)

If it is a small pond, and I am only saying this because you are in Indiana not the South, you might consider buying a bunch of water hyacinth plants from a pond supply store (unfortunately not super cheap) and then rake them out and compost them at the end of the summer. Raking out and composting is CRUCIAL, you cannot let them die and rot in the pond, you need to REMOVE the nutrients they contain while you still can! Any survivors will be 100% killed off over wintertime.

You can also stock in some of the submerged, rootless or poorly-rooted pond weeds. There are a lot of kinds and honestly I've been out of pond ecology for long enough that I dont' trust my recollections of what's invasively dangerous in Indiana - you should look it up. You then rake/dredge out as much as possible of the pondweed in late August or so and compost it. But because you will never remove all of the pondweed, there is the possibility of IT becoming a problem in the pond, so you have to be ok with that. Note that these will not do well until the water becomes somewhat clear-ish, so you have to manually remove surface scum and tackle pea-soup water *first* before submerged plants will do much good.

The second big category of "things you can do" involves encouraging the excess dissolved nutrients to become bound in the sediments, and thus harmless from an algal-bloom standpoint. The nutrient that generally limits these blooms is Phosphorus. Phosphorus has the interesting property of being poorly soluble when oxygen is present, but staying happily dissolved in anoxic (low or no-oxygen) water. Ponds often go anoxic in the bottom water in summertime, thus preventing P from precipitating out and actually liberating *more* P from the sediments.

Thus the purpose of aerating a pond (which is a misnomer, really you are just stirring the pond so that it does not stratify and the bottom water doesn't go anoxic). A silly little fountain, scaled to the size of the pond, is the most commonly-used method. It really really does help. Highly recommend.

The final thing that you want to do is think about how nutrient inputs to the pond can be decreased. If this is a small ornamental pond, clean it out (remove any festering organic crud on the bottom) and don't fertilize plants where the runoff can go into the pond. If this is a big "real" pond, don't fertilize lawn or fields that are in the watershed of the pond, or do something to divert runoff from them if they 'must' be fertilized. If the pond attracts lots of waterfowl, try to discourage them. Etcetera.

In some cases, it's a quick fix, in others (like where the nutrient problem is really severe and the pond is quite large) it can be nearly-intractable. (BTW, the barley thing can be useful in some cases as a temporary measure, e.g. to try to clear water up a bit so that submerged plants can get going, but is not a good long-term "main strategy")

Good luck, have fun,

Pat, retired aquatic biologist

 

[Wifezilla]

I seriously don't recommend duckweed, it can totally blanket a pond and you will never, ever, ever get rid of it

If you have animals that eat duck weed, you have a perpetual free food source. If you DON'T have animals that like duck weed, then it would be a problem.

 

[curly_kate]

Thanks for all the tips guys! The lake is about an acre, and the algae is pretty massive. No one's really done anything with it in years. I was thinking that ducks could eat some of the muck, but it sounds like they might exacerbate the problem. If we were to put in a fountain, would we need to clean out all the algae first, or would the movement of the fountain kill it off? Also, can you fish in a lake with a fountain in it, or will it disturb the fish too much?

 

[patandchickens]

That's a project, there.

If it were me, what I would do is (all of the following):

a) put in one or more aerating fountains (sized appropriately to the area and depth of the pond... I do not know the #s offhand, but they should be available via Google or from manufacturers);

b) cut back any trees, brush or tall weeds around the edge of the pond, so that the wind can have maximum effect on the pond and help the fountains to turn over the water;

c) do my utmost to limit fertilizer and manure-runoff inputs to the pond in all ways possible.

d) read up on pond weeds that could be stocked in next spring (not now), and think about whether any of them seemed like a good idea or not (depends in large part what you want the pond to be *for*)

e) give it a year or two, see where things stand.

Aerating will not get rid of the existing algal scum, but it will limit the extent to which eutrophication (the nutrient overload) gets worse, by limiting anoxia of bottom water and thus limiting further Phosphorus loading from sediments. If you do decide to stock in pondweed, you want to do it as early in the year as possible, so it can get the best possible head start growing and suckin' up nutrients (since whatever nutrients remain freely dissolved in the water will tend to produce algae).

(e.t.a. - I know a bunch of people who have aerating fountains in their ponds, and still fish in 'em, so it must not interfere too much )

Good luck, 'have fun' (that may not be the right thing to say in this case ),

Pat

 

[Wifezilla]

Like Pat said, the fountain will not mess with the fish. We have a large public pond near us for fishing and they have 2 big aerators in it running all the time.

The only thing I disagree with is cutting back trees. If you get aerators, the oxygen is taken care of. You NEED shade to help keep that algae down. If trimming the trees means more sunlight on the surface, you are just promoting more algae.