Sonar RTU (Ready-to-Use) Aquatic Herbicide 1 Quart, Systemic Weed Control for Duckweed and More - No Mixing or Equipment Needed - EPA Approved, Season-Long Treatment, Safe for Fish & Wildlife

Followed the instructions for a 1/2 acre pond, 2 quarts initially, then 1 more after 3 weeks and another quart 3 weeks after that. No changes for 2 months, started to feel ripped off, then magically within 5 days the pond was clear of all algae. Pretty amazing stuff.

I have a small backyard koi pond of approx. 800 gallons that got duckweed a couple of years ago from some plants I had ordered on eBay. This product is expensive but I hadn’t found a better option, so I bought a bottle and did the math to determine that I needed to add a whopping 3 ml. I double checked my work and got the same answer. So I used a syringe that had come with an inkjet refill kit, shook the bottle, sucked 3 ml out, and squirted it into the pond. It remained kind of congealed so I did mix it into the water. A week later and the duckweed turned light in color and started to die off. I skimmed most of it off and it’s obvious that it is no longer spreading. I’ll reapply in a couple of weeks per the directions but I stand amazed that 3 ml was this effective. It does not appear to be affecting my 3 koi at all.

Finally, after 40 days the duck weed is gone! After my first application (1 quart for a 1/4 acre pond) the duck weed grew faster and multiplied like crazy. I thought surely I was feeding the duck weed and not killing it, but I call the company that make this product and they assured me the Sonar was going to work but I had to be patient and let it do it's job and BINGO, after 40 days the duck weed was gone. I am thrilled!

This product seems expensive at first, but it is worth the price in my opinion. It is concentrated and treats a great deal of water for its size. The real advantage is that it doesn't require and special application. No spaying with droplets of a particular size and no need to be in or on the water. You apply it right out of the container. I do walk the edge of the pond to spread it out a little, but the directions say you don’t even need to do that. It is so soluble it spreads throughout the pond on its own. And it works when applied in the correct quantity and on the right schedule per the application instructions. No more algae.

Not only is this stuff expensive, I do not think it works. After almost 2 weeks of applying as directed, we do not see any visible changes in our pond that is invaded by duckweed. We applied this LAST year with no results. The company stated we needed to apply 4x the amount (4x cost). We waited until this year (2024) and applied a competitive product (AurmaxKnockout) and only used 1/2 the bottle and our pond is clear of Duckweed only after 7 days!!! Sepro tried to give us a "deal" of 30% off a $900+(yes I said nin hundred) product that they claimed would clear our duckweed problem. Instead I bought Knockout and only spent $100 on a bottle I only used half of!!!

We've battled Azola in our small pond for years. Twice a year, we'd have to get creative with some good old-fashioned redneck engineering, scraping and scooping out the layers by hand. The Azola always came back. Once it's there, it's almost impossible to get rid of. We tried virtually every herbicide, both legal and not-so-legal, available in California, without success. Finally, we gave this product a shot. We did our usual manual cleanup and then poured in the whole bottle in on April 27th. For weeks, nothing happened, and we were starting to lose hope. But then, out of nowhere in June, everything changed. The attached photo was taken on June 10th, just seven weeks after treatment, and for the first time in probably 10 years, we can see the bottom of the pond clearly. This stuff really worked miracles for us, and we'll definitely keep using it and sticking to the recommended maintenance.

Definitely a very stressful first 14 days. Didn’t notice much difference even with some rain that helped knock down the duckweed. Once I started to see a difference it worked very quickly. 21 days I waited to add the second application by the instructions. I’m currently a week out from third application and the pond has been very clean and duckweed free. Now under the instructions it does state that if your pond has a lot of water change meaning it will have high flow of water through pond from a stream or creek that feeds your pond it will dilute this product too much as it is a slow acting chemical. My situation is pond is currently low as the amount of rain we have received is lower than many years prior. It works very well would highly recommend but be careful of aquatic plants you like it kills everything and will even start to affect cat tails.

I have a 1/4 acre pond,4 feet deep. I have applied two quarts now over the summer. For the first quart, the weeds on the edge of the pond started turning white, but the duckweed is still there. So I applied a second quart about 6 weeks later. More weeds turning white on the edge of the pond, but the duckweed still covers the entire surface. When I applied the second application, I used a surfactant and sprayed directly on the duckweed. I have used the normal SONAR in the past and it worked for up to 4 years. I may have to switch back to that one.