Pond Boss Forums INTRO Questions & Observations DO crash and dieoff?

From E. Central Ia. As everyone here, I have my owm little psychological retreat in my 1 acre pond of which I have been very proud. One week ago I checked my pond at sunset. Has been a very bad year here, very little snow melt and drought conditions since. My pond experienced a very significant algae bloom this spring-more than I have ever seen. Water pea green and scummy. That's what I saw that evening, the next morning the water was brown and my fish did not eat. Went to work, came home,checked the pond and it was full of airsuckers, some bigger catfish (to 5 lbs) already dead. Next two days every signicant fish (cc, HbG Readear, Grass carp) became fly food. Snails floated, and tadpoles disappeared. Pond has been well cared for and has signicant aeration. My question (finally). I have several patches of Eurasian milfoil. This has died also-now just brown patches of rotting vegetation. Is this typical with DO crashes and die-off? Should I consider other causes for my fish kill? Hate to think I have been deliberately sabotaged. Any comments would be appreciated. Excuse my ignorance-Thanks- Postbeetle.

postbeetle,

I doubt that you have been sabotaged...more likely a victim of overpromotion of fertilizer or other chemical usage. Something has caused excess nutrients to build up in your pond. Fertilizer is the first thing I think of, but it can be due to other sources such as a cattle operation that has drainage into your pond. Another possible contributing factor would be the numbers of fish in the pond..if there are too many fish, lots of nutrients are present and its dry with no otherwise provisioning of fresh water, that's a recipe for disaster.

If you do think you have been sabotaged, a water test might tell you what has really happened.

It must be a very sad thing to see, very sad indeed. Hope I never go through that.

I agree with ML. I had DO crashes several times befor I quit trying to maximize production.

My condolences. You might be able to help somewhat by immediately beginning aeration.

BTW, I heard last night on the news that the heat/drought is expected to continue thru September.

Jeeezus, postbeetle. Yer scarin' me. I'm in S.E. Iowa (Columbus Junction) and have had the same weather you've had, with perhaps even less rain. I believe the only thing saving me is that there aren't that many fish in my pond, yet. Only began stocking Sept '04, but I've some nice gils and CC in there. Havent installed any aeration system yet, but seriously considering it...this dry stuff has got to end someday.

postbeetle - your quote -"Pond has been well cared for and has signicant aeration". Would you briefly explain how you aerate and for how long each day?. What is pond ave depth and max depth?
Thanks.

Mr Cody: My pond is roughly one acre in size. With lack of rain and snow the last two years it is now at 1/2 acre. I built the pond myself with an old cable 8 dozer 12 years ago. Just stocked it three years ago with CC,HBG,Readear, Fatheads, 2 Grass carp,LmB. Have added to pond each spring for two years, additional HBG and CC (50 each stocking). 6-8" origional CC have (had-now dead) grown to 5lbs, HBG at 9". I feed during summer Purina pellets, 1/2 coffeecan daily. The pond even with low water is at 12' depth at deepest and tapers to 0 at shallow end. I installed a stainless steel diffuser (made by an engineer friend) in 6' of water, with 1/2" black water pipe driven by a 1/4 Horsepower Gast rotary vane pump 800' away, in a barn. I run this 24/7 and it gives me a column of air 2' in diameter with a roil of over 3" at the surface. The pond is extremely fertile and sits in the middle of 40 acres of 10year ground not farmed for 20 years. The pond had not been stocked for 10 years and was residence to 100's of migrating ducks and geese. They brought all the usual-milfoil,cattail,snails etc. Yesterday I counted 10 turkey buzzards circling the pond-cleaned out fish until I puked. Now I just stay away. Temp. predicted here for the next 3 days to be 98-102 degrees with no rain in sight. If nothing else comes of this post, Thanks for letting me get it off my chest-Thanks-Postbeetle.

Postbettle I am slowly working (interruptions) on an explanation of why a fish kill occurred in your pond. When I finish it I will cut, paste and post it here. Stay tuned.

My apologies. I missed the significant aeration part.

Postbeetle -Situation Details
1. pond appx one acre
2. lack of moisure the last two years it is now at 1/2 acre.
3. I feed during summer Purina pellets, 1/2 coffeecan daily.
4. stainless steel diffuser (made by engineer friend) in 6' of water powered by 1/4 hp Gast rotary vane - run 24/7
5. ½ ac pond with low water is at 12' depth
6. pond is extremely fertile - residence to 100's of migrating ducks and geese. Water pea green and scummy. That's what I saw that evening, the next morning the water was brown and my fish did not eat.

fish kill opinion -analysis

Here is what I think happened in your situation.
1. Diffuser was originally placed too shallow at 6 ft deep which from your description so far -I assume the diffuser is currently sitting in about 3 ft of water due to the current low water level. In smaller ponds the diffuser should be at pond's deepest point so water is moved out of the deepest bottom area (belly) and to the surface of the pond. Even though the boil is active, the water is only being pulled from 3 to 6 ft deep which in YOUR case leaves a layer of 6ft to 10 ft of water deeper than the diffuser. The resulting water circulation from putting an air diffuser shallow is similar to that of those who move their diffuser to shallow water during winter to reduce super cooling of the entire pond. In your specific situation, even with a diffuser at 6ft deep, when hot calm weather occurs, the pond can/will stratify (form a warm layer) at level (depth) close to the depth of the diffuser’s head; in your case 3-6 ft deep. A diffuser at a shallow depth in a small pond does not create strong enough water currents to cause the circulating warm, less dense water to penetrate the cooler more dense deep water zone. The circulating upper warm water will move outward and down along the bottom contour and it seeks the path of least resistance in its return circulation to the diffuser which in your case was at a depth of 6 ft or shallower. Wind mixing of the upper layer in most shallow ponds is also at about 6 ft. The placement of the diffuser enhanced this upper warm layer. This means your pond formed a deep anoxic bottom layer (devoid of dissolved oxygen and formed a build up of hydrogen sulfide). This anoxic layer could have compounded the dissolved oxygen loss after the bloomed died.

2. Pond was fertile with a heavy algae bloom in the warm layer. Feeding pellets enhanced fish biomass. Hot weather reduced amount of DO that water can absorb. Bloom crashed, water turned brown from rapid decay of dead bloom. Heavy bacterial growth from consuming the dead bloom consumed most of the available dissolved oxygen. Weather conditions or physical conditions from the bloom crash may have helped cause a partial turnover where the upwelling water containing poisonous hydrogen sulfide might have assisted in the degradation of the top layer to cause fish suffocation. One diffuser may not be able to add enough dissolved oxygen to a small pond during a massive bloom crash. Diffusers have different efficiencies of transferring dissolved oxygen to water (bubble size and depth of diffuser are important). Blooms can be at different sizes (biomass) when they crash. A pond’s natural or normal daily oxygen consumption (BOD) also enters the situation during a crash. Together, the two will exert varying amounts of oxygen loss. One time, a crash may not kill fish whereas another time fish will die. Water temperature and the ability of water to hold dissolved oxygen also can be important in determining if fish die during a crash.

3. I think if the pond was completely mixed during the crash of the bloom the overall amount of dissolved oxygen in the entire pond might have been enough that only a partial fish kill or no fish kill would have occurred. Complete mixing of the pond might have reduced the overall size of the bloom and prevented a total algae die off.

Hind sight is always better than fore sight. Lots of possibilities in cases like this.

Mr Cody: Thanks for your appraisal of my situation. As you have concluded, it's harder to lasso the bull once it's out of the chute. Live and learn, "destiny" and all that. All the factors involved, and the consequent "cascade to destruction" were amazing to me. In such a short amount of time ol' Mother Nature slapped me up side the head so fast it made me realize there's very little we can do to control situations like this. Nothing worse than standing on a dock and seeing 3 years go down the tubes. However I didn't have this forum and availabilty of a wealth of information before. Now do-will use it to start over. Thanks for your time and help-Postbeetle.