Pond Boss Forums AERATION Systems questions DO Experiment Design Help

Good evening,

I am testing a new aeration system this winter here in MN and want to generate some meaningful data.

Experimentation will be done using small body of water (about 400,000 gallons). The pond has an average depth of 3', highly organic, and has a fish load. What I would like to do is limit the DO input to one source. Generating DO entirely from the aeration system being tested. No inputs from photosynthesis. I will measure DO in fixed spots throughout the winter. Turning the system on and off throughout the winter.

My thinking is to add black pond dye into the water until it becomes so dark, DO generated from photosynthesis stops. At what secchi disk reading could I assume this happening?

Thanks!

This will be cool!

MN,
What is the goal? If you talk to vertex and other diffuser manufacturers, they all have charted how much O2 their diffusers add to the water for a given CFM/depth. Are you trying to see something different. Please let us know.

Also. the fish will be consuming O2, how are you going to account for their usage?

Finally, I assume the BOW will be frozen over, or will there be water to air contact?

What is the goal?
I am trying to develop a reproducible science experiment in a frozen pond setting. Specifically testing for DO amounts diffused into a BOW over x amount of time using different intermittent solar direct drive aeration designs.

If you talk to vertex and other diffuser manufacturers, they all have charted how much O2 their diffusers add to the water for a given CFM/depth.
There is no data on this type of aeration system as aeration has never been done this way before.

Are you trying to see something different. Please let us know.
What I might have here is a way to aerate frozen water without the creation of thin ice. The safest way to aerate in the north. I had completed some proof of concept tests last winter but with the short winter last year I wasn't able to set up any "good science" reproducible testing.

Also. the fish will be consuming O2, how are you going to account for their usage?
Yes, the fish and the dying plant life will be consuming the DO. When running, with the bio loads, this system will keep the DO well above 8 or 9ppm in this pond setting (at least it did last winter but how much of that was because of photosynthesis). How long will the "banked DO" last once it is shut off? Once it drops to say 5ppm , how long does it take for the system to get the water back to the 8-9ppm?

Thanks for the response HF

Is the area small enough you could just cover it with a plastic tarp? Maybe a few floats or poles in the middle for support, in case the warmth under the tarp melted the ice.

IMO You are going to need to add black dye until the DO drops to zero which indicates respiration is equal to or exceeding DO production. And then you still may have some natural production of DO. I think ideally, at the start zero DO should be maintained for at least 24hrs if not longer to verify DO production is minimal or equaling respiration. DO should be measured in every 6" of depth, if not shorter intervals. Photosynthesis and diffusion of oxygen from the atmosphere are two big producers of DO in natural waters. I'm not sure your plan is scientifically feasible in an atmospherically open exposed natural pond - too many variables IMO. IMO the best way to test DO production of a new diffuser system is to use the same methods or earlier studies. This makes data more comparable as in apples to apples.

The test site would be too big to cover it will a tarp but thank you for the thought

Bill thank you for reading and given your inputs. As you suggest, it may be too much of an uncontrollable environment.

You can still give the project a try. This will give you some experience and test data for the new system. At least you are aware of some of the variables.

Thanks again Bill and there will be a lot of testing done this winter

https://imgur.com/a/zScC7

With winter almost over and all of our testing complete I wanted to pass on our failures. We have been so humbled this winter with regards to understanding aeration here in frozen waters of MN. Over a dozen ponds with fish populations being tested and monitored, my partner and I have successfully killed 3 of them. The auger and DO meter got its workout this year.

Shallow, highly eutrophic BOW's, and intermittent aeration are verrrrrrry complicated and challenging to sustain fish thru the winter. We are not giving up and have more ideas to try! Unfortunately, a simulated MN winter in the lab is way beyond our budget. So we wait for next winter

We had some limited successes on improved aerator mechanics in the frigid temps and thin ice safety features with our diffusers. Those features will be built into our next generation intermittent aerator and we will be excited to post pics with the system up and running.

Editorial: 17 years of doing small remote ponds here in MN and still I feel like an idiot. Maybe I should quit....no dam way!

Don't be a tease! Let's hear some of what you saw and learned!

and I don't even want to hear about getting your butt kicked this Winter. Mother Nature didn't even have the decency to hand me mine on a silver platter. She served it up on card board!

Thanks for the text Chad and the kind words!!!
It's been awhile since I posted here and have learned so much about winter aeration here in central MN. More questions than answers for sure but good stuff none the less (at least I think so). Problems defined, theories postulated, prototype systems built, tests conducted, and data collected. Sadly, product development was stopped this year due to a lack of market interest. Instead of letting the information die, I thought I would share some of the things we did and maybe spur a little winter time discussion.

It's been so long I don't remember how to post pictures! Once I figure that out, I will post pics of different designs we tested, our testing methods, and the results. I will give as much detail as people want. Disclaimer: These are just my experiences and I will tell you straight up, in the dozens of ponds we ran tests on, each one was unique. We did start to develop some patterns but not enough testing over enough years had been done to be conclusive. Ok, Onto the posting pic challenge

test

MNFISH!!

Great to see you post man!! I am all ears on your input on Winter aeration! I do not like and am sorry to hear that product development ceased.

How about some info on the device in the pic? It looks interesting.

As far as posting pics, I am using Imgur.com and I am very satisfied with it.

Interesting MNFISH2. Is that direct drive aeration with a containment structure to keep the ice "thinning" effect to a minimum? Thank you for passing the info along!

Got the picture stuff fixed thanks to wbuffetjr. My format going forward will be random and most likely completely unorganized. When I get time, I will add content. Simply a download of information as I remember it or others ask (about 18yrs of experiences in total so this could take awhile). Hope this helps my fellow brothers/sisters in the country of frozen waters!

Pictured below shows one pond set up that was intended to:

1) Give us a "controlled" lab setting. And I use the word control very loosely here!!

2) Test different direct drive, solar powered, bottom diffuser systems. Changing the amount of input power generated by the array, run times in cloud cover,compressors and very cold temps, ect.

3) Assist in the creating of an aerator system that would reduce the risks associated thin ice.

Everything we have done and tested was with solar powered systems with no batteries.

Notice the picture below shows the system right after it was installed. The picture in the previous post show it after a couple of days and "froze" into position.

The system pictured in the previous post and this post, uses both bottom diffusion along with forced air. The diffuser moves water up the water column (like a traditional system) into the "hatch". While that is happening an air blower pushes air into the hatch across the open water. Inside the hatch is where the O2 infusion and pond gases exchange is happening. The system maintains open water 24/7 with runs times of 3-4 hrs/day on average. The cover of the system which is not shown in the pictures below (the hatch cover) contains the inline blower. If you look at the photo in the previous post, you can see the ports labeled. The inline blower is pumping ambient air across the water. It would be comparable to a 20-25mph wind across an open body of water.

What is not to love! Looks simple and effective!

So awesome! I can imagine it would be tough to quantify the DO rise for the whole body of water, but could you tell any 'practical' impact on fish survival? Or did you get any formal data (net or seine survey, shock survey, et al) on fish number and class sizes?

This may be proprietary info, so if so, just ignore me. Thanks for sharing what you have!

Very cool! So is the whole rig sitting on kind of a miniature floating "dock" so it follows the water/ice level?

That's impressive. First time i've seen the blower moving air across the open water concept. Novel and original. Thanks again for sharing.

It did prevent the "thinning" effect and makes it so you can walk right up to the aerator without the fear of thin ice for most of the winter. As am sure you aware, its those 6+ inch snows that become scary with intermittent aeration. Animals or people walk onto that ice not knowing how little is underneath them. This concept was designed to eliminate that fear. As spring approaches, it did open up around the system

We did quite a bit of DO testing along with the mechanical iterations. And as you might expect, it was difficult to eliminate variables to produce solid test data. We did, however, discover how important open water is to aerating a highly Eutrophic pond. The compressor pushing the bubbles does very little as compared to the ambient air to water interface.

I think that is such an important point, that I personally almost forget. The oxygen diffusion into the water occurs AT THE SURFACE. I'll generalize but say, we all love seeing the 'boil' of the aerator, but it's not the bottom or bubble column where the magic is happening.

Do you feel like it improved over winter survivability, in any way that you could tell or measure?

Ok DrLuke...This is where I think it starts to get good. Again, these are my experiences and would need to be validated by others....

1. We were able to drive the DO up at a rate not seen by any intermittent bottom diffuser system (under ice covered waters). This is point one and not too shocking when you really understand how O2 is absorbed into the water column. The forced air inside the hatch is a significant amount of O2 over a 3-4hr run time. We figured the 4 square feet, with the forced air and the water movement from below inside the hatch, would be equivalent to a 20' diameter hole of open water.

2. How we used the hatch to deliver air and Cleated Copper into the water column. We were able to slow the BOD. Significantly enough to get a 3 ppm gain in 300,000 gallons of water in less than 8hrs (the series of tests we performed in stained water at night, eliminating photosynthesis O2 production and a YSI Optical DO meter was used).

I know what the experts are going to say and they are right, I don't have enough scientific data to support these statements. But here is what I think is happening...

Intermittent aeration (less than 6hrs/day run time) under the ice, in Eutropic waters, the bacteria on the pond bottom are getting enough O2 to reproduce and actually flourish. By mid to late winter they are consuming most of the O2 and no matter how much is replaced, with a 6hr run time, the bacteria multiply at a rate that makes the O2 gain zero to negative. Once the ice comes off, very large quantities of O2 diffuse into the water column, UV light penetrates the bottom and the DO jumps

Beneficial bacteria,a Eutropic ice covered pond, with intermittent aeration....not good for the fish population, IME (in fact we killed 2 test ponds last year with it)!

This one is built on a "dock". Posts run from the platform to the bottom. I think a floating setup would be pretty cool to try

Wow! I realize I need to be careful regarding final conclusions from your research, but the hypothesis/testing/theory aspect of what you've done is extremely interesting. And it highlights one of the aspects of my personal pond management that I find the most challenging: attempting to measurably modify a biological system. I've always over simplified (i.e. low DO = dead fish, higher DO = live fish, ergo aeration = always good for fish). But in a BOW, with a full spectrum of life competing for the resources, changing one or two aspects/resources very often does not have the impact I expect (or really, hope for).
Don't get me wrong, I am not discouraged by this, just chastened a bit. There is solid data that supports the benefit of 'macroscopic changes' to our ponds (like structure, water depth, et al). I seems there is lots to learn about how to effectively impact the microscopic side.

Really, really good stuff MNFISH! Thanks for sharing your work with us!

I agree with you DrLuke, the sort of thing MNFISH2 is doing is fascinating to think about. There was a post last month about infusing dissolved oxygen into the column of a bottom diffuser that I found interesting that would seem to be applicable to this system as well, particularly if there is ice on the pond and the partial pressure of O2 can be increased between the ice and water surface. I have wondered if these systems of oxygenation/aeration could be tested in a standard swimming pool that is frozen. This would largely eliminate the biological variables when measuring DO at various depths. Obviously the information would not be directly applicable to a pond, but it might help to understand what is a reasonable expectation in a biological setting. As alluded to in the post from last month, could it be that DO can be increased in the water by pumping O2 under the ice and not letting it escape through a hole cut in the ice?

MNFISH

What do you think would happen to a floating unit once the ice began to form? Could ice get a hold of it and tear it up? I guess it would have to do with how it is built.

I only built systems that were proof of concept and affixed to the pond bottom. So I can't honestly answer that. There would be more development work on the blower system as well. At your pond, what would be the coldest day of the winter (ballpark)? What is the thickest your ice gets in a winter? (again ballpark)

This brings up another concept that we were not able to completely test but wanted to explore more. With remote location ponds, big bodies of water, that were highly Eutropic, was there a way to create "O2 safe zones" for the fish. To sustain an entire larger pond above lower lethal would be very very expensive with direct solar drive units.

Last year when my buddy went up he estimated the ice to be 18"-24" thick. Coldest day so far this year has only been in the single digits. Last year I saw negative single digits a handful of times.

Great experiment. I once had a solar aerator stop after days of no sun. Then on the first sunny day I checked on it and saw my buoy was still frozen in. I thought the aerator was down but when I got closer I could here it was running. There was dome of ice holding my buoy up and a 30 foot circle of air under it! I was surprised by this to say the least. I grabbed my ice drill to see if there was air pressure under the ice which there was! The odds of this were slim as one crack in the ice would release the air, then water, and it would open up an area. As I stared at the dome I realized several benefits of what was happening. First the safety of having solid ice over it. Secondly I was thinking about how open water becomes super cooled when aerating in the winter. I have noticed the fish avoid the area and stay in warmer water near the bottom. The dome was insulating the aeration area.

There was one drawback I thought of when I had the dome of ice, that was that gases could not escape. Assuming that your prototype is not air tight this should not be an issue. Anyway keep us posted. If there would be a way to aerate without open water in the winter I would be behind it 100%

What compressor did you use for this solar setup?

Thomas Diaphram 1/10hp Pump. 1.4cfm freeflow

We did not come to the same conclusions. It is our belief the doom of ice is a real detriment to O2 transfer and added more unpredictability to thin ice locations and thus created more danger.