Pond Boss Forums AERATION Should I aerate? Another Questions about air and oxygen?

Ok so does it matter oxygen wise if I create a bunch of bubbles near my dock in 4 feet of water or do I have to have by bubbles out in the middle of the pond? Does either one oxygenate the water just as good? It would be much easier to do something off the end of my dock then in the middle of my pond is why I am asking?

Thanks,
RC

The deeper you inject air into the pond, the more lifting (movement) of water you get out of it. The more water movement, the more oxygen added to the pond.

Center placement of the diffuser(s) would likely allow better flow around it(them) as well, I think. But that would depend on pond geometry.

Just an FYI ICYDN relatively the bubbles don't directly contribute to adding oxygen to the water. As they rise to the surface they creat water flow upwards or as Theo says "lifting (movement) of water". The water in the bottom of the pond flows up & spreads across the surface of the pond eventually repeating & circulating the entire pond of water. It's the contact with the ambient air at the surface that oxygenates the water.

The water at 4' of depth should have adaquate oxygen so your objective should be to oxygenate the water close to the deepest part of the pond.

Ric very well stated you sure your not in the aeration biz?

In my youth, I had aquariums for years that had air stones (diffusers) in them. During this entire period I thought that the air stones "injected' the air into the water thereby oxygenating it. It wasn't until I became a pond meister and found this site that I learned the science behind how an aeration system really works. Fortunately my aquarium fish either knew how the process worked or didn't really care.

The transfer of oxygen in the bubble is less than 5%. We are only pumping 21% oxygen down any way so very little oxygen is transferred.

The "magic" occurs when we have pumped the bottom water (anoxic) that contains Hydrogen Sulfide, Carbon Dioxide and Ammonia to the surface. Because Oxygen content in a water molecule is concentration and temperature dependent, we have to off-gas those bad gasses and make room for an oxygen molecule.

Now that we have done this at the surface, that layer of good oxygen water will move along the surface until the energy has disapated. It will continue to be layered upon itself until that original layer is brought back to the bottom.

Yes, a 4-foot pond should be well aerated but I have seen cases in FL where due to heavy algae blooms the sun heats up the surface and a thermocline is present. Since the sun is bloced by the algae, anoxic conditions begin to occur. The oxygen molecule now can not break though the thermocline since this water is heavier and the pond now begins to separate.

This is why close observations of the pond are necessary.

Ok,I have rambled on enough.

RC51....Honda Lover? I have a Super Blackbird 1100XX Had it on the track to a speed of 188mph! What a rush!

Thanks Greg but I've just been hanging around here a while picking up a thing or two from people like you & Cary. You guys are great!
Speaking of great teachers, anyone heard from BC lately?

Great post!

One main feature all are ignoring is the amount of oxygenation by the aquatic plants ESPECIALLY the phytoplankton due to its very high numbers (often in the millions) per every ounce of water. If ponds did not have phytoplankton and relied soley on oxygen diffusion from the atmosphere, just about everyone even those with good aerators would have regular and frequent fish kills. Pond plants as a group produce around 70%-85% of the pond's total amount dissolved oxygen throughout the year.

I can't figure out why more people can not grasp this concept despite me frequnently repeating it.

Well that I CAN answer, we're pig headed.

Two features or characteristics of DO in water verify my statement above. For those that regularly measure DO in water, 1. note how fast and how often on sunny days oxygen can become supersaturated with dissolved oxygen (greater than 100% saturation). That does not happen especially at subsurface depths in uncirculated water due to diffusion from the atmosphere. It is the result of plant photosynthesis. 2. When DO is low at dawn note how rapidly the DO will increase in the pond water by late morning, noon or early afternoon. An increase of 10-11 ppm of DO can occur (even at subsurface depths unexpsed to air) in just 4-6hrs of early day sunlight. That rapid rise in DO was not from diffusion from the atmosphere, the rapid increase was due to plant photosynthesis.

If exposing oxygen deficient water to the air at the surface added lots of oxygen to water, then aeration with strong circulation alone would be adequate to save all fish during an extreme or low DO fish kill. Low DO and loss of DO was likely due to the LACK of photosynthesis by the abundant plant and bacterial mass (respiration) which again points to the importance of plant photosynthesis for maintaining and producing dissolved oxygen in aquatic habitats.

Yet another post to add to my word document "about pond oxygen by Bill Cody." I've edited this document three times this morning.

Bill, I gave/give you credit for educating ME at least on this & most other pond related info. Thanks to you I am at least able to make an attempt at an answer to some of the questions posted.
I DID learn where the majority of oxygen in a living breathing pond comes from. But I forgot it & felt I was missing something which is why I asked . I'm just not the teacher you are & didn't explain as well. Thanks for pounding it in my head again.

Am I wrong in thinking RC's 4' placement of aeration would not accomplish his goal of oxygenating the entire pond?

The way I think of it the aeration IS oxygenating the entire pond via the circulation even though aeration is not actually the greatest contributor of oxygen to the water.

BC, I guess it was not mentioned and I preach the same btw because it is as you know give and take. You many tiem s have well below saturation in the morning hours with thick phyto bloom especially after an overcast day.

I have some killer data from Hilton Head island SC on how an undersized system can negatevly effect DO, same water you have id phyto on twice. If a system does not handle BOD then it can lead to lower Do and a fishkill. Aeration is a serious business and you better make sure to get an expert to do it right.

Fish kills due to low DO are basicaly due to more respiration (oxygen use) is occuring by all life forms in the water (bacteria to fish) than the available previous day's net oxygen production from atmospheric diffusion and photosynthesis.

Most low DO fish kills begin at night when oxygen consumption is typically longest and greatest. When DO consumption depleates dissolved oxygen supply to low enough levels, usually before sunrise, fish start dying even though an aerator can be running. If the aerator was highly or even adedquately oxygenating the surrounding water all the fish would have to do is swim into the upwelling boil to survive which rarely successfully happens.

Properly sized bottom Aerators should adequately mix the entire pond or a majority of it to result in a mixture of a large amount or volume (top to bottom) of highly DO saturated water due to vertical mixing of highly oxygenated "photosynthetic" DO enhanced top water. This DO saturated water volume should be large enough to provide enough DO supply for all the oxygen consumers until sunshine reappears and photosynthesis can begin the daily process of creating a surplus DO for the next dark-light cycle.

Problems with this theory occur when cloudy days and/or phytoplankton/plant losses occur which result in less DO or not enough DO production during that daylight period. Also the warmer the water is the less DO it is able to hold or contain. Thus rapid DO losses often, not always, occur in the warmest temperatures of the year.

There are rare instances where Phytoplankton will become too abundant and combined respiration from all plants and bacteria(DO night usage) will exceed the DO bank account. Whenever the previous day's DO bank account is too low for the dark period DO consumption, fish begin to die near dawn. If not enough plant photosynthesis is present in the next day period, fish will continue to die throught the day even though a supposedly water oxygenating bottom aerator is running.

Actually for best efficient use of the bottom aerator during a fish kill the diffuser should be moved into shallow water where it only repeatedly mixes or circulates the top photosynthetic DO enhanced water. Situated on the deepest bottom area, the diffuser is trying to mix too much oxygen deficient water, while incorporting too little additional DO thus resulting in keeping the overall DO in the pond, lower than if the diffuser was not operating. Thus operating a deeply situated air diffuser during a fish kill is counter productive. For better chance of helping the fish move the diffuser into shallow water where any air DO diffusion results are kept in the upper photosynthetic layers where the fish are gasping for DO.

Great info Bill... Thank you for breaking it down.