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Help with killing duckweed please!

I would like to start off saying this is in the wrong forum but I couldn't find anything related to this and definitely dont want to grow it. This forum has the most hits so I am giving it a shot!

My grandfathers 10 by 20 yard pond is completely taken over by duckweed from the horses down the road pissing so much and a flood washed all that crap into his pond. We have tried a chemical product known as Reward and it may have gotten rid of a bit but now it is back and healthy. It has wiped out all fish and even killed off a lot of vegetation.

My idea is to take a huge double crossed mesh screen and rig a net out of it and drag it through the lake for hours until I have almost all of it out and then throw tons of tilapia to eat up the remaining.

If anybody has experience please help!
 
you need to spray diquat pretty much every year.

aeration helps. so does some species of carp i think?

but diquat will kill it back pretty quickly and its not harmful to what ever fish you have left. my dads pond has a similar issue... i looked into it for him and diquat is the logical answer.

you basically kill it off then start aerating or introduce the stupid carp fish and this is how you manage it.
by aeration i mean like a fountain or pump or an actual air compressor with aeration stones. just get the surface moving. if possible you want to well up the shit close to the bottom without picking up scum and sludge from the bottom itself.

if you pick up the shit on the botton you can cause worse problems for your fish. the shit at the bottom of your pond is full of anoxic partially digested duck shit and what ever... fish piss i guess. dredging it up will introduce even more nutrients to the ponds water column.
 
Grass carp will do the trick.  Get some triploid males - completely sterile.  Once they eaten it they starve.  Then they pretty easy to catch with a hook baited with lettuce.
 
But given the nutrient influx I would say its best to treat the source as well.  Wherever the inflow is I would dig a channel (wide and shallow) and plant it with all manner of reeds - Phragmites are best.  This will reduce the nutrient load before it gets into the pond.
 
Grass carp will do the trick.  Get some triploid males - completely sterile.
Yes, exactly this ^^^

But given the nutrient influx I would say its best to treat the source as well. Wherever the inflow is I would dig a channel (wide and shallow) and plant it with all manner of reeds - Phragmites are best. This will reduce the nutrient load before it gets into the pond.
But be careful on this part. Some areas consider reeds (especially cattails) to be invasive plants here in the US. In certain parts of our state, there are efforts to eradicate them. So double check in your area before doing this. Not suggesting that it might not be completely OK, but reeds can be a bigger pain in the ass to get rid of than duckweed.
 
queequeg152 said:
you need to spray diquat pretty much every year.

aeration helps. so does some species of carp i think?

but diquat will kill it back pretty quickly and its not harmful to what ever fish you have left. my dads pond has a similar issue... i looked into it for him and diquat is the logical answer.

you basically kill it off then start aerating or introduce the stupid carp fish and this is how you manage it.
by aeration i mean like a fountain or pump or an actual air compressor with aeration stones. just get the surface moving. if possible you want to well up the shit close to the bottom without picking up scum and sludge from the bottom itself.

if you pick up the shit on the botton you can cause worse problems for your fish. the shit at the bottom of your pond is full of anoxic partially digested duck shit and what ever... fish piss i guess. dredging it up will introduce even more nutrients to the ponds water column.
Thanks so much for all of this info!!
RobStar said:
Grass carp will do the trick.  Get some triploid males - completely sterile.  Once they eaten it they starve.  Then they pretty easy to catch with a hook baited with lettuce.
 
But given the nutrient influx I would say its best to treat the source as well.  Wherever the inflow is I would dig a channel (wide and shallow) and plant it with all manner of reeds - Phragmites are best.  This will reduce the nutrient load before it gets into the pond.
Thanks man! We had some cattails in the past around the pond but this crap destroyed it.
One final question, should I try to remove a lot of the duckweed by manual means or just toss some carp in and let them do your job?

As far as chemicals we want to try other means. we treated with sonar and it was like 250 bucks for 8 oz here... Worked for a bit but its back. I
 
i do some storm water design professionally and id seriously warn you off of trying to bio swale your way out of this situation.
 
unless you have serious earth moving equipment... you are not going to be able to stop the eutrophication imo.
 
its not impossible, but without serious design measures you are going to be wasting alot of your time and money trenching and planting this and that.
 
what you would need is a topographic survey... then identify the drainage areas( mini water sheds), then calculate the design flows for something like a 2 year storm, then start engineering the bio swale.  
 
depending on elevations, grades etc you might need to impound water with mini damns or wiers... or provide storage via some semi impermeable basin filled with say... bull rock or crushed stone and geotextile etc.
 
then you have to engineer for the sheet flow during higher than design rain fall events . basically a way for the system to gracefully over flow out of the bio swale and directly into the storm water collection system. even with the bioswale operating perfectly... during winter and cold periods the runoff might still contain appreciable amounts of phosphate and nitrate owing to low soil and plant activity.
 
 
the whole bio swale thing is huge right now... cities and state cream their pants about this green eco shit.  mostly these things are engineered into new highway or roadway construction projects... there is alot of concern right now about pollution from cars running off into storm water flows and then into rivers and estuaries.  mostly motor oil... transmission fluids, gasoline and other crap.
 
 
bio swales and bio treatment is also huge in waste water treatment... the discharged treated waste effluent is still high in phosphate and some nitrate or ammonia depending on how the WWTP is set up.
 
discharging this treated waste into a biological impoundment or artifical wetland can take that phosphate down to almost 0. idk about the nitrogen probably not 0, but reduced quite a bit. the artifical wetland would also make a cool palce for birds and shit i imagine, but idk.
 
again though when its cold as shit this is all reduced to some extent.

http://www.ebay.com/itm/Diquat-Water-Weed-and-Landscape-Herbicide-Quart-bottle-/301804113237?hash=item4644ed4d55:g:oDgAAOSwkZhWTyB-
 
PepperAaron said:
One final question, should I try to remove a lot of the duckweed by manual means or just toss some carp in and let them do your job?
I'm guessing you don't know what we're talking about when we talk about grass carp. :D

 
Wikipedia said:
The grass carp grows very rapidly. Young fish stocked in the spring at 20 cm (7.9 in) will reach over 45 cm (18 in) by fall. The average length is about 60–100 cm (24–39 in). The maximum length is 1.4 m (4.6 ft) and they grow 40 kg (88 lbs). The grass carps maximum weight is 99 lbs. According to one study, they live an average of five to 9 years, with the oldest surviving 11 years.[4] They eat up to three times their own body weight daily. They thrive in small lakes and backwaters that provide an abundant supply of freshwater vegetation
You probably don't need more than one for the area you quote. And it may still starve.

We had (2) of these in a pond that was roughly an acre-and-a-half. They kept the water crystal clear.
 
queequeg152 said:
i do some storm water design professionally and id seriously warn you off of trying to bio swale your way out of this situation.
 
unless you have serious earth moving equipment... you are not going to be able to stop the eutrophication imo.
 
its not impossible, but without serious design measures you are going to be wasting alot of your time and money trenching and planting this and that.
 
what you would need is a topographic survey... then identify the drainage areas( mini water sheds), then calculate the design flows for something like a 2 year storm, then start engineering the bio swale.  
 
depending on elevations, grades etc you might need to impound water with mini damns or wiers... or provide storage via some semi impermeable basin filled with say... bull rock or crushed stone and geotextile etc.
 
then you have to engineer for the sheet flow during higher than design rain fall events . basically a way for the system to gracefully over flow out of the bio swale and directly into the storm water collection system. even with the bioswale operating perfectly... during winter and cold periods the runoff might still contain appreciable amounts of phosphate and nitrate owing to low soil and plant activity.
 
 
the whole bio swale thing is huge right now... cities and state cream their pants about this green eco shit.  mostly these things are engineered into new highway or roadway construction projects... there is alot of concern right now about pollution from cars running off into storm water flows and then into rivers and estuaries.  mostly motor oil... transmission fluids, gasoline and other crap.
 
 
bio swales and bio treatment is also huge in waste water treatment... the discharged treated waste effluent is still high in phosphate and some nitrate or ammonia depending on how the WWTP is set up.
 
discharging this treated waste into a biological impoundment or artifical wetland can take that phosphate down to almost 0. idk about the nitrogen probably not 0, but reduced quite a bit. the artifical wetland would also make a cool palce for birds and shit i imagine, but idk.
 
again though when its cold as shit this is all reduced to some extent.

http://www.ebay.com/itm/Diquat-Water-Weed-and-Landscape-Herbicide-Quart-bottle-/301804113237?hash=item4644ed4d55:g:oDgAAOSwkZhWTyB-
Damn you know your stuff.. We will definitely look into diquat if the carp doesnt do the trick.
solid7 said:
I'm guessing you don't know what we're talking about when we talk about grass carp. :D

 

You probably don't need more than one for the area you quote. And it may still starve.

We had (2) of these in a pond that was roughly an acre-and-a-half. They kept the water crystal clear.
Wow, so I wouldn't need to use a net to get any out before adding the carp? I just worry that if I dont remove any duckweed they'll die like the rest of the fish in the pond. Turtles and frogs are living though
 
PepperAaron said:
Wow, so I wouldn't need to use a net to get any out before adding the carp? I just worry that if I dont remove any duckweed they'll die like the rest of the fish in the pond. Turtles and frogs are living though
These fish are purpose built to survive in stagnant water. I've seen them in algae laden waters that were less than 10" deep. I've seen them coming to feed on top of water that was solidly covered with duck weed.

They will be fine. But as with any sort of plant, you should check with your local regulations before introducing these fish.
 
if those carp are as ravenous as all that... then maby hold off on the diquat.

lol it would be fun to watch, day to day ... a few of these carp getting all fat on duck weed.

can you get them as decent sized juveniles? or do you just have to get tinsy ones?
 
queequeg152 said:
if those carp are as ravenous as all that... then maby hold off on the diquat.

lol it would be fun to watch, day to day ... a few of these carp getting all fat on duck weed.

can you get them as decent sized juveniles? or do you just have to get tinsy ones?
If your pond is 10 X 20, there is no way you want more than one. A few of them will end being hand fed in no time at all. (unless you let them starve)

We bought ours 20 years ago, and they were already almost adult. If they lived more than 5 years, I'd be surprised, because they had done their job within about a year or two. As for procuring them, I know how they work, but I don't really know much more than that, anymore...
 
solid7 said:
These fish are purpose built to survive in stagnant water. I've seen them in algae laden waters that were less than 10" deep. I've seen them coming to feed on top of water that was solidly covered with duck weed.

They will be fine. But as with any sort of plant, you should check with your local regulations before introducing these fish.
We are on the way to grab us some carp! We are going to get anywhere from 3-6 and once it starts reducing we will cast net the carp and eat them, leaving one or two for the pond.

Would there be a reason to not get a few extra?
 
The Internet said:
Recommended Initial Triploid Grass Carp Stocking Rates
Average Plant Density / Stocking Rate (# of fish per acre)
Low Plant Density / 5 fish per acre
Medium Plant Density / 10 fish per acre
High Plant Density / 15 fish per acre
 
Hell I posted the pictures last night and delete them from my phone. Now I see theres no last message so I have no picture.

The guy acted like he knew plenty enough about it. He is the man he has always went to about stocking his pond an back in his prime our grandpa had a damn nice pond. The carp were about six inches long with mouths on the lower front of the face and he showed me the difference between grass carp and these other carp. He did say they weren't sterile but our pond will unlikely have spawning conditions especially if its overran with duckweed.

he said however buy 10 pounds or so of tilapia babies and letting them party in it would do more than Carp and we said maybe if the carp dont work.
 
Lots of fish love Duck weed, I put some in my aquarium and was gone in a couple days. Grab some feeder fish from a pet store and see what happens, but then if the pond is now filled with chemicals it might kill the fish lol.
 
The chemicals were last year so im sure they're gone, it is also safe for fish so it claims. The fish man mentioned that the carp could be diploid not only triphloid could this make any difference?
 
PepperAaron said:
Hell I posted the pictures last night and delete them from my phone. Now I see theres no last message so I have no picture.

The guy acted like he knew plenty enough about it. He is the man he has always went to about stocking his pond an back in his prime our grandpa had a damn nice pond. The carp were about six inches long with mouths on the lower front of the face and he showed me the difference between grass carp and these other carp. He did say they weren't sterile but our pond will unlikely have spawning conditions especially if its overran with duckweed.

he said however buy 10 pounds or so of tilapia babies and letting them party in it would do more than Carp and we said maybe if the carp dont work.
the problem with ponds like your is low oxygen... the algae is basically primed and ready to go from all of the nutrients in the water, and when temps get high they go absolutly nuts and consume all the nutrients they can, then die back and bacteria then go nuts and consume all of the oxygen in the water.

dont hold me to this... but i think some fish are able to go to the top and gulp air and some are not? i think this is why carp are ideal for shitty ponds... im not a fish person, just going of some vague memory i have. i could be very wrong here.

regarding chemicals killing the fish. diquat is very safe for fish... well maby not "very", but its less toxic than shit like copper i believe. the rates your spray diquat are based on surface area. you can put the stuff in a backpack sprayer... but for the most part ponds are too wide for such applications, i think most people use pressure washer type wands with chemical injection equipment. you spray it out over the surface then the shit dies off and decays into the water a few days later.

diquat wont kill slimes or algae grasses though. the concentration in solution is too low to kill anything.

if you have that shitty slimy grass that grows up from the bottom you might have to try something else.

i still highly reccomend you aerate the pond if you can afford it. a little quarter horse floating sump setup would probably work for something that size, but you might check online for more concrete information. adding oxygen makes everything better. aerobes can digest more of the organic material, and the TSS(total suspended solids) should drop depending on just just how much air were talking about.

do you know how waste water treatment plants turn shitty brown turbid sewage into cleanish low turbidity water? its mostly just aeration. the aerobes consume the available nutrients then go dormant and fall to the bottom.its alot more complicated than that, but thats like the overarching principal here...
 
Their are some Solar Aeration Devices, that would be a very good solution to get some oxygen in their, just a pump with a hose with water running down a piece of slate or something natural.
 
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