Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Draining pond and need some advice...

Hey guys I have about a .75 acre pond thats a fairly flat 12' depth.... It get covered in duckweed every summer and seems to be a fish kill of all but a PLETHORA of green sunfish.... Im planning on draining this sucker down with a 4' pic siphon here soon... I have come to the conclusion that hydrated lime will be my best bet for killing the fish but my question is will that dose of hydrated lime kill the duckweed too or is my only option to add expensive sonar.... Id like to drain it dry completely for a while but I will only be at my camp for a couple weeks and don't really have the time to make that happen ... What are my options?

The pond is actually more like 1 acre when full and i went around with a tape measure one day and measured a bunch of 12' spots so hopefully there will be a low spot to drain to!

Good question - Eric West recently posted that lime treatments will kill vegetation, but didn't expound on it much. No clue on the duckweed. Will you be excavating organics and silt from pond once it's drained? If so, removing a significant volume of organic material through excavation might cause the duckweed to stay away for good. It's certainly worth a shot to drain, nuke, and refill and see if it returns. If so, you can always treat later. What type of fishery are you planning on?

I read that somewhere maybe the same article thats why i asked actually... I would like to get the organic matter out... How much of a layer is there usually? the pond is 20 years old. Depending on how long that duckweed has been in there there could be a ton of matter just from that huh?
As far as a fishery i am still undecided... I have another pond on the property that is 2.25 acres and it was stocked laster year bg re fh and bass ....This pond i posted about sits directly behind my house and I would like to possibly change it up so have have more options on the property ya know... also like to swim in it possibly? what would be good alternatives to compliment the other pond?

I thought I read on here that duckweed is prolific in ponds that have a lot of organic nutrients in it, and poor aeration.
If I was draining it, I would get the muck out of there at the same time. No way to tell how much muck there is in there. Well, actually there is. I think Esshup has described a way to do it.

Then since it is near your house, run aeration to it. You could wait on this and do after it fills up again.

would aeration and bacteria alone prob make a big difference in the duckweed?

Walking in the pond will relate pretty quickly the depth of the layer of organic material on the pond bottom. Your feet will sink into a layer of black ooze. I'm guessing your pond likely has 12"+ layer. I have used both excavator and dozer on ponds at my place, depending on the nature of the pond bottom. Too much material and a dozer will get stuck, need long reach boom on excavator to remove in that case. I think it's a good idea to excavate if you are draining, get a new lease on life of the pond. If you do so, I would bet the duckweed would not find establishment easy with removal of nutrients. Clean slate for you, blank canvas.

Duckweed is an indicator of highly nutrient rich waters, and minimal wave action.

Bacteria and aeration will help, but to turn around a pond that is like that is like using a 5 gallon bucket to empty a swimming pool that has 4 GPM of water entering it.

You can empty the swimming pool, but it will take a long time, and you have to keep at it or it will fill back up again.

Draining, removing the nutrient rich organic layer on the bottom, THEN aerating and using bacteria after it refills would be the route I recommend.

Hydrated Lime will kill all living things when the pH is raised, and kept, above 11 for a few days. Most plants get killed quickly from the roots and leaves being burned caustically.

If killing duck weed, plants are easy, but the seeds in the bottom muck/soils need to soak in the high pH water, or be removed.

It costs more for the amount of lime needed to raise the pH above 11, but still way cheaper than Sonar.

To kill fish, drain as low as possible, then use what is left in the pond to mix and spray the lime over the entire "full pool" area until all areas have soaked in lime and water flowing back to the water left runs clear.

Be sure to take Rex's advice here....I missed the 'mix and spray' part of this when I did mine last spring....and now I'm dealing with a full pond still containing 2 of the 3 species of fish I was trying to get rid of.

so by that you mean i need a a hose on the pump with a nozzle to pump the water from the pool once I've spread the lime and spray it on all the banks that were under water and keep doing it until the water is clear.....

I just made a slurry in 5G buckets and dumped into the pond until the PH exceeded 11. Nuked everything - no problems, no sprayer, very simple. Add lime to bucket of water mix and apply. Actual application to 1/3 ac 18" depth pond took about 30 minutes.

You also didn't have bullheads or other fish that hid in mud or puddles, did you? Not treating the entire pool area well could let sneaky fish survive.

Yes, there were a few bullheads, but primarily BG. I did treat the entire remaining water per this method - walked around the margins, pouring slurry, then into the pond repeating to ensure I was mixing it was well as possible. Three weeks ago had a client eradicate BH from his pumped down pond using this method also - pumped pond down to 3 puddles about 12" deep and applied a slurry from buckets until PH was achieved, then waited and watched everything go belly up. My entire pond was treated in this way, puddles included - that's important to do for sure.

I am up in Canada and my pond is being completely taken over by milfoil, and as I'm sure you know we have very little available to us in the way of chemicals. My pond is 1/2 ac. about 8 foot average depth. If I were to start over would lime be a way of completely eliminating all milfoil. If it were not for the 10 feet of rock all the way around the pond I would drain and re dig but replacing that rock is not in the budget.

With milfoil moving further north I find it frustrating that the Canadian officials refuse to look at the available science and how they can help stop or at least slow the movement of exotic/invasive species with herbicides. I hope Hydrilla never moves up there. It's here in Indiana and close to your border.

If the milfoil is there I don't see how you can keep it out for good. It only takes fragments of milfoil to spread.

What are the chemicals that are legal for you to use?

I can't find any that is why I thought maybe the lime will work. It is the seeds I'm worried about. I plan on draining the pond and doing a small renovation before I connect it to my new pond (both 1/2 acre). If I use lime for a few weeks then drain renovate and keep it dry for the summer do you think I have a chance a complete removal of the milfoil.

I honestly don't know. I DO know that draining and letting it sit dry over the winter, frozen solid won't kill them.