Water pump for aeration?

[sgbotsord]

I've read here and elsewhere that most the the aeration is a result of surface water turnover, rather than absorbing air from the column of bubbles.

Some thought on this would concur. If I pump 1 liter per minute of 1 mm3 bubbles, I'm putting about 1 million bubbles per minute, with an area of about 1 square meter. The bubbles take far less than a minute to rise, so I have a fraction of a square meter at any given time. Flip side of this: The bubbles are under pressure, and also have surface tension effects that increase the gas transfer.

When the column of bubbles, and the entrained stream of water reach the surface, they spread out in a layer of movement with some degree of turbulence. This area is far larger than a square meter.

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Ok: Based on this, would a cheap submersible sump pump be an effective aerator?

* Put a sump pump in a cage to keep it out of the mud and put it 1 foot off the bottom.
* The initial pipe is 1.25" (common size)
* That pipe goes into an open 3" pipe with about a foot overlap. The 3" is supported so that it's centered on the smaller pipe.
* After a couple more feet, the 3" similarly is centered in a chunk of larger pipe.
* The larger pipe ends about a foot below the surface.

The idea is to entrain more water in the flow, moving more water at slower speed to maximize surface mixing.

This could also be done with a special purpose pump that was essentially made like a submarine prop that was fairly large, but spun fairly slowly. Think of the contrast between a floor mount oscillating fan and a ceiling fan on slow.

Is this a standard approach?

 

[poconojoe]

My head exploded trying to comprehend what you were saying!

No disrespect...
You may enjoy analyzing the situation in detail, but for me, I like it simple.

Any method that breaks the surface tension will help with aeration.
A small pump disrupting the surface, an air stone or two, a waterfall, a fountain.

I definitely have overkilled when it comes to aeration.
I have two air stones, a spillway and a fountain made out of a bucket sitting on the bottom.
The bucket has a 550 gph pump covered with lava rock and a PVC pipe comes out of the pump which ends just below the water surface.

Again, no disrespect...
We don't know if your pond is 600 gallons or 6,000 gallons.
You gave a lot of detail in describing your planning or ideas, but gave none about your pond, fish or filtration.
How many gallons does the pond hold?
Dimensions of you pond.
Fish size, type, amount.

 

[sgbotsord]

I didn't specificy size as I wanted to discus the general concept, independent of that.

If you care, the pond is approximately 14,000 square feet, 14 feet deep, and roughly 800 cubic meters (200,000 gallons)

I have no fish, lots of frogs.

I want to reduce the amount of duckweed, and reduce frog die off at turnover.

 

[poconojoe]

Wow!
200,000 gallons!
That's huge!
Now I understand your thought process.
You are dealing with something on a very large scale.

I only asked the size because aeration requirements for a small pond would be much different than a very large one like what you have.
Think of one of those plastic ponds you buy in Home Depot compared to your "lake" of a pond.

Again, it's all about breaking the surface tension of the water.

With a pond that large, how about one of those really nice fountains?
That will break the surface tension, sound and look really nice.

There are also submerged oxygenating plants that you can add.
A nice field of Anacharis or something similar growing on the bottom might help, plus it would make a great place for fish to forage, hide, etc.
You might already have a lot of growth with a pond that size.

Aim for water movement and breaking surface tension.

 

[brokensword]

I didn't specificy size as I wanted to discus the general concept, independent of that.

If you care, the pond is approximately 14,000 square feet, 14 feet deep, and roughly 800 cubic meters (200,000 gallons)

I have no fish, lots of frogs.

I want to reduce the amount of duckweed, and reduce frog die off at turnover.

I doubt aeration will dissuade duckweed but agitating the surface will at least push it/keep it at aeration's edge. Typically with larger bodies of water, and esp those farming fish, a large diffuser and air pump is used. A fountain is also employed. Part of your analysis is flawed, imo, because the 'bubble' has more surface area upon breaking the water surface and the water on this bubble is now exposed to the air. When the wind oxygenates a natural pond/lake, it does so by creating waves (thus more surface area), much like bubbles. So,you can aerate by using a pump but imo, it's less efficient.

 

[sgbotsord]

This is what I had in mind.

 

[Jhn]

@sgbotsord If you are trying to eliminate frog die off in the pond over the winter you just need something to create a hole in the ice for gas exchange. Fountains or water movement will push duckweed away from the area of moving water.

The submarine prop idea is used around fixed piers to keep ice from pulling the piles up, just called a deicer or marine deicer. These will keep a decent size opening even with a foot or so of ice in surrounding water. Just need something to tie it to, to keep it a foot or two below the water surface.

 

[sgbotsord]

It's more complicated than that. The pond covers over with duckweed. This reduces light to lower depths. Lower depths become anerobic. Strong wind mixes anerobic and aerobic water. Die off. Stink.

Duckweed sinks in autumn. Oxygen demand on water.

So need a solution to do two things:

* Reduce amound of pond covered in duckweed.
* Eliminate anerobic water.

 

[Jhn]

Not really that complicated….Running a fountain or something like the deicer that moves the surface of the water to prevent the duckweed from covering the pond in its entirety, will eliminate the build up of harmful gases. When the ponds surface gets covered in its entirety in any way be it by duckweed or ice it inhibits gas exchange causing the water to become a toxic mess to its inhabitants. The solution is the same, water movement at the surface to prevent this from occurring.

If this isn’t a viable option then adding an inhabitant to the pond that would consume the duckweed could be another solution.

If in your original post, the idea is to put more oxygen in the water just disturbing the top of the water, with a sump pump will provide some oxygenation but won’t be as effective as an aerator or some sort of fountain with a splashing effect.

 

[brokensword]

I concur with jhn; what he's proposed is used by many ponders/fish farms.

 

[Ronfire]

My 6 waterfall work for aeration.