Problem with duck weed on a small lake

[Charlie Two Tracks]

I was going to put this in the Outdoor section but couldn't figure out where, so here goes:
I have a small pond (60'x 300') behind my trailer where I camp. That thing gets covered by duck weed each year and looks real bad and cuts all light from the pond. I know that moving water helps kill the duck weed so I was thinking of either putting some kind of fountain in it or forcing air through a hose that is anchored at the bottom of the pond. The pond is only about 5' deep right now. Got any ideas on how to get this weed under control?

[R.M.]

I've seen ponds with a small windmill that aerates it. Don't know if that would help with the weeds or not.

[dbosman]

Surface agitation is the key. Gold fish can be part of a cure, but generally not seen as such by catch and eat fishermen. The problem with inexpensive solutions is depth of the water. Pumping air into water quickly brings up pressure issues. That's why rain/parking lot run off "ponds" have fountains in them. Windmills generally don't work well in water for duck weed as that type of pond is usually below the level of a steady wind. A taller land based wind engine, geared to a propeller -about 20 feet into the pond could do the job.

[oldred]

I use Aquashade blue dye and it works wonders! This stuff kills weeds by turning the water a nice shade of blue that defuses light and kills the weeds by inhibiting photosynthesis, it's completely nontoxic and does not poison the water!

[MtGun44]

I think the underlying problem is excess nitrogen in the water, possibly from feritilizer
run off. Any way to slow or stop this? The plants are reacting to a food source.

Bill

[quilbilly]

debosman has it right about surface agitation. Your pond is shallow enough that you can run a poly air line to a couple spots in the lake and attach an air compressor. I am not sure how often or long it has to be run but I am sure it needs not be run full time in a "smaller" pond. That setup will increase fish productivity as well since it will break up the anaerobic layer near the bottom.

[Freightman]

Had a swimming pool behind me that the people went bankrupt and moved off from, the algae and duck weed got bad so I went and threw some tillopa in and in a couple of weeks the algae was gone and at the end of the summer caught them and ate them. Put them at 2-3" and at the end of the summer they were well over a foot. Don't worry they will not survive the winter as they are tropical. That was my solution and the fish are cheap at the tropical fish store.

[jdam169]

I know you didn't ask for a herbicide suggestion but here is one anyway. In my bass pond I treat duckweed with a product called Reward. The active ingredient is Diquat. You mix it according to the labels instruction and spray over the top of the duck weed. Make sure to use a surfactant to aid in absorption of the spray into the duckweed.

[higgins]

Check with your usda ag. extension agent and your state fish & wildlife agency. They may even send someone out at no charge to assess the situation and suggest solutions.

[Charlie Two Tracks]

These are good ideas. I think I will try the air route first and see what happens. I have a descent air compressor but I don't want to run it for hours on end. I have and electrical motor and need to think of what to use for the air compression itself. Any ideas? There is no run off going into it but it is in the middle of the timber and surrounded by trees. I think that the leaves are building up at the bottom of the pond. I don't believe that the oxygen level will allow fish to survive right now. I put some minnows in a fish cage and after a couple of hours they were dead. This was late in the fall and the pond had been covered all summer. No other vegetation is on the bottom of the lake. I believe that the duck weed blocks off all the sun penetration.

[quilbilly]

You are exactly right Charlie. Lack of sunlight and dying algae sucks the oxygen right out.

[hiram1]

take some 1 in.plastic pipe drill 1/16 holes in it about 3 in.apart about 40 feet put 2 big rocks on it and lay it in your pond just push it out in it.worked for me in arkansas.i run it for about 45 min per day for a week 7 day week

[oldred]

Since the pond is not deep an aeration pipe could be used with a squirrel cage type blower (furnace fan?) instead of an air compressor. Since this would be MUCH more efficient than using an air compressor it would be far more practical to run for longer periods of time, it only works with the pipe down to a depth of a few feet however but I think you mentioned the pond is only about 5 ft deep?

Don't dismiss that Aqua Blue pond dye I mentioned it really does work quite well. It will clear up murky water by killing algae and weeds and it it does so without toxic chemicals, I have used it for over 12 years now and wouldn't try to get through a summer without it..

[John Allen]

Charlie, the asian carp will get rid of duckweed. You have to get a permit for them in PA and buy them from a place that keeps them from reproducing.

[Charlie Two Tracks]

I will check on the blue dye. I don't believe that the carp would survive until I get some oxygen in the water.

[turmech]

You are exactly right on the fish not living until you oxygenate.

My pond was wonderful for years. Duckweed took over and killed what appeared to be 1000's of fish mostly brim.

I bought a whole chemical kit online. It was kind of expensive (I think around $250). It did include the blue die among other things and step by step instructions. I also added a fountain pump I made form a sump pump in a floating trash can. I would be happy to dig out the info if you like.

All the fish posted already eat the duck weed. Only the gold fish will handle cold IIRC. And not all fish are allowed to be stocked in every state.

My pond is crystal clear now and I hope to restock it.

[dbosman]

Given Charlie Two Tracks' location in Northern Illinois, obtaining plant eating fish shouldn't be a huge problem.
Except for the locking lid on a very large transport container.
https://www.youtube.com/watch?v=epOescKTgUw

[turmech]

Yea I guess I should have said fish which won't take the pond over and you may actually want in the pond when your done.

[texassako]

Straight out of How to Identify and Control Water Weeds and Algae: "For areas less than 1 acre, tank mix 1 part Cutrine-Plus to 10 parts Weedtrine-D. Add non-ionic surficant and apply at a rate of 1 gallon per 1/5 acre." Certain dish soaps have non-ionic surficants in them and say so on the label, or you can buy it. You just spray it on, but make sure you get it all in one go or it will come right back. Fish like carp are not the answer, they might not eat it and they stop eating much of anything when they get big.

[Fishman]

Charlie, lots of well meaning advice here bit a lot of it probably won't help you.

First thing is to accurately identify the weed you have in your pond. Duckweed is often used as a generic descriptor for water weeds. True duckweed isn't rooted and floats on the surface. The whole plant is about a half inch across.

Aeration will not solve the problem but it won't hurt. An air compressor is the wrong tool for the job.

True duckweed is best treated with a product called Sonar. Reward can work but rarely gets it all.

Grass carp are ineffective on duck weed.

PM me if you have any questions. I'd be glad to help. Same applies to any other members.

Finally, something I know something about! :)

[00buck]

A guy I know raises Talapia and offered me $5 a bucket for duckweed. They eat it

[pipehand]

A guy I know raises Talapia and offered me $5 a bucket for duckweed. They eat it

I've heard that chickens like it too, but you have to harvest it for them- they won't eat it like ducks do.

[Fishman]

A guy I know raises Talapia and offered me $5 a bucket for duckweed. They eat it

They sure do, but they die when water temps hit the mid-50's. Since Charlie is in Illinois, he'd have to restock each year. Also, they won't get it all, likely not even most of it.

[Charlie Two Tracks]

I read about them being temperature sensitive. I will go through these ideas one at a time and see what I can do. That duckweed makes the pond look really bad and without fish, I'm sure it is producing mosquitoes also.

[Bad Water Bill]

They sure do, but they die when water temps hit the mid-50's. Since Charlie is in Illinois, he'd have to restock each year. Also, they won't get it all, likely not even most of it.

Fish just like us need oxygen to survive. Over the winter most if not all of the duck weed will at least go dormant and drop to the bottom. Wind across the lake will assist in oxygenating the lake.

When the lake reaches a temperature your selected fish can survive in put the fish in a large container that is as warm as the water from where you purchased them.

Now place the large container in your lake and leave alone for a day or so. Now slowly add lake water to the container till you have at least a 50-50 mix.

At that time the fish should be adjusted enough to survive in the lake.

Now to save your fish over the winter move your lake to SOUTH TEXAS for the winter. :bigsmyl2: