Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants New pond owner with watermeal problem

New pond owner and first time poster. My family just bought a farm and there is a small pond in the front of the house with a dock. About 1/8 acre and 17 feet deep in the middle. It's covered in watermeal and possibly duckweed. It has fish in it. The previous owner said he just dumped 10 gallons of diesel in it every year to clean it. Has anyone ever heard of that? And if he's done that each year would the fish be safe to eat? Thanks for any advice.

Welcome to Pond Boss.

Duckweed = DW and watermeal = WM are a tough problem.

You can do a search and find many threads on the topic. They can be controlled by mechanical or chemical means but both take work and diligence. If you can't find a thread then post and I will find one. Only use approved chemical methods not diesel .

See these for reference

http://aquaplant.tamu.edu/plant-identification/alphabetical-index/common-duckweed/

http://aquaplant.tamu.edu/management-options/common-duckweed/

WM and DW are signs or ecological signals of a very organic nutrient enriched usually very old or dramatically aging pond close to or trending toward wetland/swamp conditions. Anything chemically you do will be very temporary as far as rejuvenating the pond. Consider for your long term budget to have it drained and rebuilt with all the years of slop and chemical contamination (diesel fuel) and residue removed. IMO diesel fuel applications have severely hindered the overall biological and chemical health (ecology) of the pond water and sediments. You might want to get a real measurement of the true pond depth. At 0.125 acre it is very doubtful that it is deeper than 7-8ft.

I don't know if it makes a difference or not, but the banks of the pond are very clean. No overhanging trees or anything like that. When it fills the overflow goes into the pasture. If I drained it, what expense am I looking at? Would a rented powerful submersible sump pump be effective in doing this? Also, I called the conservation biologist and they suggested Sonar AS.

What about Tilapia to eat the duckweed.

Look for a trash pump to pump the water out.

I would verify the water depth as Bill suggested, before worrying about anything else. If you hadn't done this yourself, others likely "assume" it to be better than reality.

Sonar AS will work. You have to get an accurate measurement of the water volume in the pond, and make sure that you keep a 90 ppb concentration for at least 30 days.

I got my 8oz $220 bottle of Sonar As in the mail today. 2 questions. Chance of rain for the next week, do I need to wait to apply it? And, I have a pump in the pond that shoots up a fountain 20 feet. Can I run that after applying Sonar AS to help aerate the pond at the same time, or will that hurt the effectiveness of the Sonar?

Rain, in and of itself, isn't a problem with SONAR.
A rain-induced "flow-through event" (discharge of treated water) is definitely of concern. Basically, if a pond has a high potential for transient water due to its current level or an extra large water-shed, it really isn't a good candidate for SONAR treatments - where the full value of the product isn't achieved unless it remains contained within the treated pond for 30, 60, 90 day, or even longer...
If transient-water is likely, CLIPPER is probably a better option for duckweed, watermeal; whereas AQUATHOL might be a better candidate for several submerged weed species.
Operating your fountain post-application will do nothing but assist the treatment's dispersal throughout the pond; so don't hesitate to run it as you please.
BTW,SONAR GENESIS (in 1-gal jugs) would've been a much better value than SONAR A.S. in the 8-oz bottle. 1-gal of GENESIS has twice as much active-ingredient as 8 oz of A.S., but is only $100 more. Then again, if 8-oz of A.S. is enough to treat your pond - and you won't need any more (ever), then the A.S. was a logical choice.