Hello, I'm the owner a home with a 1.55 acre pond included. Unfortunately, the pond is infested with duckweed and water-meal! It is covering 100% of the ponds surface, and has completed suffocated the pond. I have recently purchased a vertex aeration system to try an aid in the ponds health. I have read through some of these forums about the different ways to kill these unwanted plants. I am strongly considering the fluridone option, and was wondering how many ounces I would need to cure the pond. I'm not opposed to the diquat mix, but the idea of maybe having to spray 6 times scares me. The average depth of the pond is 6ft with a deep hole of 9ft.

You could also use Clipper.

I have a 4.5 acre pond with similar depths as yours that was completely covered with duckweed 5 weeks ago. Today I can report no living duckweed! I also had copious amounts of filamentous algae (almost all gone now). I topically sprayed with 37% diquat (20 oz in 15 gal sprayer) and Cutrine Plus ( 40 oz in 15 gal sprayer) plus 3 oz nonionic surfactant. Mix diquat in 15 gal water first, then add Cutrine, agitate then add surfactant, spray within a few hours of mixing. I initially used just diquat but adding the copper significantly increased the effectiveness. I would caution to only treat 1/3 to 1/2 of pond at a time to avoid fish kill. My brother has 7 acre pond and sprayed entire pond with some fish kill. I also have shallow water aeration diffusers running 24/7. Started the aeration one week before I started spraying. I repeat sprayed every three to seven days as soon as I saw new growth. Once I started down this path, I was a little afraid I might kill all my fish so I called in the state pond management expert for our area. He completely supported my course of action. I have sprayed 5 or 6 times using a 15 gallon battery powered sprayer on the back of my golf cart and use the boat for areas I can't reach with the cart.
I also used pond dye, two applications.

1st picture is one week after 1st treatment on May 14. The other two were taken today.

Another note: my brother used fluridone in his pond to the tune of about $4000. Killed all the duckweed for about one month, then came back over next two years heavier than ever. I have spent about $450 on my pond so far including buying the 15 gallon sprayer. Have found great suppliers for diquat, copper and pond dye at very economical prices. If you are interested I can email you those websites,

Unless one changes the cause of the problem,,,, the same problem or a new one usually returns after eradicating the offending problem/symptom. Duckweed-watermeal are usually caused by many years of accumulation of organic materials that eventually contribute lots of the combination of nutrients and dissolved organics that favors growth of duckweed. Duckweed is very rare in nutrient poor relatively new ponds.

I totally agree Bill Cody. I believe my main problem is the amount of leaves, pine straw, etc from the trees, scrubby shrubs that have grown up around the pond going into the pond each year. Have cleared out almost all the source of the leaves this spring from the perimeter of the pond. I know it will take several years for the muck caused by all this organic material to clear up.

However, in our area, the pond expert says he is seeing duckweed growing rampant in all ponds, new or old, low ph or high ph, nutrient rich or nutrient poor. The state extension office really is not sure what is going on.

my experience...diquat didn't touch my watermeal. This weekend I did just spray the whole pond with Clipper and so far, it looks like it's killing it.

Thanks for your response guys. I have recently just sprayed the pond for the first time. I used 2 gallons of tsunami, 8oz of clipper, 3teaspoons of surfactant mixed with only 2 gallons of water. Like you, my dad was able to borrow a 15gallon battery powered sprayed and that baby sprayed a little to quickly imo.. We ran out of spray really quickly being that we only added 2 gallons of water, but that is what Andrea at Sanco industries suggested. After we ran out of spray so quickly, I started to get a little depressed. We barley made it around the pond once. I later called Andrea that day and she said we were moving to slowly, but we would still be surprised with the results. I can tell we did make a dent in the duckweed as there are parts all over the pond that are turning brown. We used a paddle boat to spray. I was moving us along while my dad was spraying from the back. I am going to spray again in 10 days with a similar mixture. I may add a few more gallons of water, but Andrea said I needed to come out with guns a blazing. I surely will be moving a lot quicker next time.

That is unbelievable to think it is the same pond! When I was a kid our 1/2 acre pond was taken over by duckweed. We put the dye in it as well as half a dozen 2 lb grass carp and they cleaned it out that summer. You could walk to the dock and see trails/holes where they ate their way around.