Pond Boss Forums INTRO Questions & Observations Complete Duckweed Covered BOW

Long time lurker, first time poster. I purchased a property in May with a 2/3 acre pond that previously had cattle in it as a drinking source to the 40 acre pasture. The depth of water ranges from 4' to deepest of 8'. Some areas of 6'. It is protected on 3 sides by hills and trees, so it gets little wind on pond surface. Prior to me, there were no fish. I stocked in late May FHM, BG and YP. I installed an aerator immediately, prior to stocking. Most all of the summer the pond had 100% Duckweed/watermark covered surface. I run the aerator 7pm -7am, not during the day as the heat seemed to cause problems with compressor. I had a week stretch where the compressor didn't run because of a blown capacitor. I can't remember if that period of time was while I had 100% covered surface or not. Now I am questioning if any of my stocked fish would have survived? Would the DO crash that quickly during the day? More details can be provided if asked, as I don't want my initial post to be any longer than it already is. Thanks for the help, and what an awesome resource this site has already been.

Duckweed infestations can be deadly. GENERALLY, in an oxygen crash, some small fish survive by going to shallow water. But, for practical purposes, you will be starting over after killing off the weeds.

Am I imagining things or am I seeing more and more pondmeisters on this forum with problems that seem to be aeration-related??

I was planning on buying an aeration system for one of our BOWs (6.5 acre) next spring but after reading some posts I am unsure. I keep going back and forth on this decision. It seems like any mistake you make has potentially deadly consequences. And it seems easy to make a mistake.

We have never had a fish kill on this BOW and it has produced pretty good fishing over the last 45+ years. I am trying to make habitat improvements, keep to a harvest schedule and keep better records.

While we do have some FA problems in this pond I fear trying to "Fix what isn't broken" may be a bad decision. BM61.

Judging by aerial photos from satellite, duckweed was a problem before aeration. I have seen no dead fish and am aware duckweed can be deadly. I am curious if 100% cover as I described guarantees fishkill or not necessarily

I don't see much duckweed around here but a friend of mine 20 miles north had about a half acre pond that was always completely covered with it. It had some huge flatheads and channel cats but very little of anything else. I suspect that was because of big catfish predation rather than the duckweed.

Someone mention Duckweed?
2 acres of it

Just one of the many uphill battles I faced when I first moved here:


Pretty difficult for sunlight to penetrate through that!

Did fish survive in that BOW?

I did have a fish kill right at that time but I don't believe that was the direct cause as I was doing a lot to the pond at that time, coupled with several cloudy days and a 3" deluge of rain in a 12 hour period. The late-great Ted Lea described my fish kill as the result of a perfect storm. And I'm sure the blanket of DW was a contributing factor.

DW can be a serious problem with DO and other matters. It is often associated with highly fertile waters/land. It does block the sun light and reduce O2 as a result. It can get 2 feet thick (depending on species). Its reproductive potential is tremendous . Some species can double in 24 hours. Shallow DW ponds in northern locations area real challenge (reduced O2 because of DW and subject to DO related winterkill due to depth). Aeration can help with DW if it is very vigorous. Turning over the DW can kill it(turned upside down with roots up). Also aeration will add DO to pond.