Pond Boss Forums AERATION Systems questions SUPERSATURATION IN FISH FARM

HI Everybody,

just recently joined. I have a 75 acre fish farm,and this season we r experiencing a strange phenomenon of supersaturation of DO, sometimes even up to 300%. Due to which we have had a fish kill.
Last year it was due to lack of it ,this time it's exactly the opposite. Looking back we had an aeration system installed, 9 hp and 21,12" diffusers, but it had no effect and the fish kept on dying.On discovering it was supersaturation we shutoff the compressors and started draining our pond and adding freshwater.

My questions to U r,

a) what to do in times of supersaturation of DO ?

b) how much aeration is required for this pond? compressor hp, no of diffusers, size of diffusers etc.(temp of water nowadays around 32/33c, av depth 6ft)

Welcome to Pond Boss. A few facts may help. Give us the facts on your pond or ponds. Size , depth , type of bottom , history of the pond , water source and quality , amount and type of fish and feed, etc.

Supersaturaton of DO is caused by excessive planktonic algae and some factor that causes the excess DO to remain in the water. Typcially, as the DO concentration reaches above 120-150% it diffuses into the atmosphere. Obviously your pond conditions allowed the DO to continue to accumulate. At supersaturation oxygen bubbles accumulate on the fish gills and eventually causes death as the condition progresses.

Thank u for your inputs.

We had stopped feeding and fertilization etc, and since we are also draining and adding fresh water there is v little plankton/algae in it currently.
We have commenced feeding but continue to drain.
Somehow it's continuously supersaturated for the past 1-1/2month. The whole column (abt 6ft deep) is saturated.

It's one unit 75 acres, poly carp fish farm, around 63,000 fish initially and after die offs about 59,000.

Water source is seepage water from a river. Before 1963 the river used to flow from here but after the construction of head-works it's flow was diverted.So technically this farm is a portion of the river bed,mainly sandy soil. It had a lot of weeds and floating plants i.e water hyacinth etc.Now after alot of efforts it's clean.Some portion was removed manually and a bit more by using paraquat.

I also question the accuracy of your DO meter. Do your dead fish show signs of gas bubble disease? Typically supersaturated DO conditions do not continue into the early morning hours. I also think there is probably something other than supersaturated DO that is causing your fish deaths, maybe algal toxins? The following study shows that bass bluegills, crappie shiners and trout all tolerate well supersaturated DO conditions including a rapid increase or decrease of DO due to direct transfer from super-saturated to saturated water.

https://kb.osu.edu/dspace/bitstream/handle/1811/2620/1/V33N02_110.pdf
Gas bubble disease
http://www.advancedaquarist.com/2014/8/fish
https://www.adfg.alaska.gov/static/species/disease/pdfs/fishdiseases/gas_bubble_disease.pdf

Thanx Bill,

we too thought that our DO meter was no gd. So bought a YSI pro ODO. The readings r the same. A little high ammonia too. May b that is because the eco system is not working properly? The water we r pumping in is also high in ammonia. Could that also b an issue?
Ours is a carp fish farm.How do they tolerate such phenomenon ?

What are your readings using both DO meters (your old and your new one) in the local stream nearby or in tap water in your bathtub?

hard to imagine in water that is turning over by you pumping more water in from an outside source that any machine can get the SAME reading in a 6' column of water.

Actually quite similar readings on both , but I'll recheck. It's a 73 acre body of water and the pumps have just been installed to cool the water temperature, decrease supersaturation and bringing stability to the water. Incidentally it has alot of ammonia. So technically we r pumping in ammonia with the result that there is a plankton bloom, as we had fertilized it recently too.
It is v strange to have 6ft of water supersaturated.

ANY REMEDIES WHICH COME TO MIND ?

See this about water quality interpretation. Don't know if it will be applicable to your species but good general info.

https://srac.tamu.edu/serveFactSheet/262