Pond Boss
Posted By: DADx4 Aeration killed fish overnight - 06/14/18 01:40 PM
Put in a HiBlow 100 pump and a diffuser in the deepest part of a 3/4 acre pond. Depth at the moment is 9 feet. Pond is 25 years old. Water feeds in during heavy rain from a couple other upstream ponds. Murkey water. No surface algae or heavy vegetation. Clay foundation.

I ran the new unit for 5 or 6 hours yesterday. This morning there were tons of fish on the banks. Some were laying there still getting Oxygen and many others were dead. I saw a couple of my big bass (10lbs) laying there trying to get Oxygen, but tons of Bluegill and crappie were dead. I didn't notice any of my catfish on the banks or floating.

Any tips on why a short duration of aeration introduction caused such a harsh fish kill so quickly. I could smell a bit of 'fishyness' when the aerator was running but not overwhelming or sulfur smell.

Posted By: Acoursey Re: Aeration killed fish overnight - 06/14/18 02:06 PM
Aerators are more about water movement than aeration. With the idea being that they mix the water layers so the deepest water is brought to the surface. You should have started while the water was cold and a thermocline had not yet set up, or installed the airstone in shallow water and slowly moved deeper( 1 or 2 feet a day) to prevent the anoxic water from mixing too quickly. You likely released an incredible amount of nutrients as well with it being an old pond.
Posted By: Journeyman Re: Aeration killed fish overnight - 06/14/18 02:13 PM
That's a tough lesson to learn! It's likely 25 years of decaying matter made the bottom a toxic wasteland that the fish were able to avoid.
Posted By: BrianL Re: Aeration killed fish overnight - 06/14/18 02:30 PM
There are start-up procedures for aeration systems to prevent that from happening.

You start at 15 minutes a day until no smell is coming up from the water. Once no smell double time, Stop at any interval that smell returns, until no smell then continue to double time.

The aeration system itself does not add O2 to the water, it is about water movement.
Posted By: Quarter Acre Re: Aeration killed fish overnight - 06/14/18 04:50 PM
Terribly sorry to hear about your fish kill!

I would say that you have brought too much water up from the bottom, too fast, that was void of oxygen. This bottom water mixed with the upper levels of water WITH oxygen. This would reduce the overall oxygen levels and cause the fish to suffocate or nearly suffocate.

This water movement that occurred also brought up gasses that typically collect and stay near the bottom. These gasses can be poisonous.

I'm no expert and hopefully you will get a more specific explanation to the cause, but at this point you need to know how to move forward without making things worse. Is your aerator running now? I would suggest that it stays off until your situation has been thoroughly evaluated.
Posted By: wbuffetjr Re: Aeration killed fish overnight - 06/14/18 04:57 PM
That's terrible. Sorry to hear it.

I had to run mine 15 minutes per day for a week due to the smell before I could increase to 30 minutes per day.


It can be a very slow process. It took me quite some time to be able to get up to 4 hours.
Posted By: DADx4 Re: Aeration killed fish overnight - 06/14/18 06:15 PM
Only ran it for about 6 hours but during the heat of the day here in Texas, with turnover probably already going on. I see now why this happened. I've been sick to my stomach all day. Big clean up this afternoon in store for me.
Will start slow with 15 minutes a day moving forward. I did run it for an hour the day before with no issues, so I moved to 6 hours the next day. I know now that was a poor decision and have this terrible incident as a grim reminder for anyone else that might see this thread when starting up an aeration for the first time.
Most things you read on the web talk only about adding aeration and the huge benefit, but few places get into the proper way to introduce the system. Thank you all for your input. I'll be back with more on this thread as things evolve if you are interested to hear.
Posted By: DrLuke Re: Aeration killed fish overnight - 06/14/18 06:43 PM
Hang in there bud. Many of us have been there, and really do know how you feel. Won't be too long and you'll have healthier water to work with, which is one of the key foundations to a great fishery.
Posted By: BrianL Re: Aeration killed fish overnight - 06/14/18 09:32 PM
This is a WAG on my part, but I would wait a couple weeks before doing anything else with the aerator. Give things time to settle out, then start back slow.
Posted By: DADx4 Re: Aeration killed fish overnight - 06/17/18 03:20 AM
Day 1, approx 50 fish.
Day 2, 10 fish.
Lost mainly BG, some smaller bass and crappie, along with one big channel cat.
Today there were none dead.

Will start slow on the next go-round with aeration, only 15 min a day.
Any product recommendations to speed up the toxic muck clean up? Bacteria?
Posted By: Clay N' Pray Re: Aeration killed fish overnight - 06/17/18 10:58 AM
Originally Posted By: DADx4
Day 1, approx 50 fish.
Day 2, 10 fish.
Lost mainly BG, some smaller bass and crappie, along with one big channel cat.
Today there were none dead.

Will start slow on the next go-round with aeration, only 15 min a day.
Any product recommendations to speed up the toxic muck clean up? Bacteria?


My opinion, run aeration for a complete summer season before considering any chemicals. Keeping DO in that deep water will do more than any chemical will.

(I'm in the first summer of aeration in a 30 year old farm pond)

The smell will get worse before it gets better. One thing I've learned so far- everything has to happen slowly.
Posted By: snrub Re: Aeration killed fish overnight - 06/17/18 09:39 PM
Originally Posted By: DADx4
Put in a HiBlow 100 pump and a diffuser in the deepest part of a 3/4 acre pond. Depth at the moment is 9 feet. Pond is 25 years old. Water feeds in during heavy rain from a couple other upstream ponds. Murkey water. No surface algae or heavy vegetation. Clay foundation.

I ran the new unit for 5 or 6 hours yesterday. This morning there were tons of fish on the banks. Some were laying there still getting Oxygen and many others were dead. I saw a couple of my big bass (10lbs) laying there trying to get Oxygen, but tons of Bluegill and crappie were dead. I didn't notice any of my catfish on the banks or floating.

Any tips on why a short duration of aeration introduction caused such a harsh fish kill so quickly. I could smell a bit of 'fishyness' when the aerator was running but not overwhelming or sulfur smell.


Like others have said, you mixed the nasty bottom water too quickly with the good water the fish were living in. It could have caused an O2 problem but the more likely cause of the fish kill was all the nasty toxic gasses of the lower water ruining what good upper water you had.

Ideally you would start up aeration in such an old eutrophic pond in the cool of late winter early spring when O2 would be less likely an issue. But even then you would want to mix the lower toxic water slowly with the upper good water. This gives the toxic gasses time to off gas in small amounts over time at the surface. In the heat of the summer the slow start up just becomes even more important.
Posted By: DADx4 Re: Aeration killed fish overnight - 06/28/18 06:25 PM
Update:
I've been ramping duration up each day a little bit at a time. Running 4 hours a day currently. This slower process seems to be doing ok so far. The aeration started churning up a lot of BG algae growth but this appears to be slowly subsiding.

Fish seem to be ok. One interesting increase in activity is the carp have been eating like crazy! Not sure if the aeration is making them more hungry or what but they are eating away at growth along the banks and grass trimmings in the water after mowing.
Posted By: BrianL Re: Aeration killed fish overnight - 06/28/18 08:15 PM
Are you running during the day or at night? Better at night, as it won't heat your water up as much.
Posted By: Flame Re: Aeration killed fish overnight - 06/28/18 08:36 PM
Just a note for comparison... my pond was only 2 years old when I added aeration. And it already had a terrible rotton egg smell. I never expected that in such a young pond but gradually increased and all went well. Point being for others new to ponds....it does not have to be very old to get that obnoxious dangerous smell!!
Posted By: Quarter Acre Re: Aeration killed fish overnight - 06/28/18 08:41 PM
That's a good point Flame, My pond is just over a year old and I can get that smell walking in the shallows. I do not get it when I turn on the aerators, but I am still bringing it up slowly.
Posted By: DADx4 Re: Aeration killed fish overnight - 06/29/18 04:52 PM
Brian,
Running during the day during the slow startup but a good point. I'll be shifting to nighttime runs now that the durations are getting into the 6hr range and the system seems to be doing well.
thanks for the tip!
Posted By: Bocomo Re: Aeration killed fish overnight - 06/29/18 07:46 PM
Originally Posted By: DADx4
Brian,
Running during the day during the slow startup but a good point. I'll be shifting to nighttime runs now that the durations are getting into the 6hr range and the system seems to be doing well.
thanks for the tip!


Heating issues aside, oxygen levels are at their lowest in the early morning hours. Plants make oxygen during the day and use it up at night. Set your timer to run through the pre-dawn hours.
Posted By: warmouthy Re: Aeration killed fish overnight - 07/01/18 10:41 PM
Originally Posted By: Bocomo


Heating issues aside, oxygen levels are at their lowest in the early morning hours. Plants make oxygen during the day and use it up at night. Set your timer to run through the pre-dawn hours.


Yeah, 5 AM to 8 AM is what I used to do. I'm just getting my old pond back in shape and will be careful to start slowly after reading this thread. There's no hurry since my fish are just fingerlings now and not using much O2. New member here, there sure is a lot of good knowledge on this forum.
Sorry to hear of your crisis DADx4.
Posted By: The New Jerry Re: Aeration killed fish overnight - 10/21/19 01:13 AM
Originally Posted By: DADx4
I know now that was a poor decision and have this terrible incident as a grim reminder for anyone else that might see this thread when starting up an aeration for the first time.
Most things you read on the web talk only about adding aeration and the huge benefit, but few places get into the proper way to introduce the system.


I'm about to dive into aeration, skimming posts to learn about psi and cfm requirements. I'm 100% sure that your post saved me from doing exactly the same thing. I was planning on running two diffusers in a small 26yr old pond, 24/7, from day one.

Thank you.

-Jerry
Posted By: Bill D. Re: Aeration killed fish overnight - 10/21/19 01:54 AM
My pond was new when I installed my Airmax aeration system but their instructions were very clear for startup in any pond, old or new. 15 mins the first day, 30 mins the second day, 60 mins the third day, etc. If you smell a strong rotten egg smell, dwell at that time until the smell goes away before continuing to increase the time.
Posted By: Charles Crews Re: Aeration killed fish overnight - 05/01/20 09:23 PM
I have a 3/4 acre pond that is 7 ft deep and has bass and a few bream. It is about 19 years old and has never been taken care of. I want to start with aeration but after reading this I may wait until fall to start since I am just south of Houston, Tx Should I try some bacteria this summer to help a little or what to start getting the bottom muck taken care of. Also where is best place to get info on aeration systems and needed flow rates?
Posted By: Freg Re: Aeration killed fish overnight - 05/02/20 03:00 AM
If you follow the advice posted on this thread you should be fine starting aeration this spring. My pond is about 40 years old and had never seen aeration and I started it last spring following the advice on here of starting at 15 minutes a day and doubling it each day and no issues.
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