Aeration

[dieselplower]

I have seen mike Gannon spamming every pond site he can find on facebook. A skimmer really does very little to increase surface area. It might bring different water to the surface but an aerator will do so at a much greater rate.

 

[max384]

A SKIMMER is actually more effective at aeration than most bubblers or waterfalls. it's constantly moving, and "virtually" increasing the waters surface area. this is where aeration and gas exchange takes place. wont help much with the freeze over tho.
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just a little info on skimmers and aeration....
The pond skimmer does more than clear the surface of the pond. Pond skimmers increase oxygen levels in ponds helping to further purify the water, and of course provide rich oxygen for your koi and pond fish. Pond skimmers can do as much or more than any sort of submerged aerator, and they do not disturb the surface of the pond, allowing for nice visibility and reflections to be enjoyed from the surface of your pond.
Did you know that most oxygenation for ponds take place by way of the ponds surface area absorbing oxygen directly from the atmosphere. Those air pumps we use that create thousands of little bubbles that rush to the surface of the pond and explode really do very little to oxygenate. For oxygenation to occur those bubble need to have contact time with the pond water so they can give off the oxygen but they move so fast that there is really minor oxygenation that takes place. It is where the bubbles break up the surface of the water that the oxygenation takes place. Well a pond skimmer is constantly and rapidly breaking up the surface of the pond too. Pond skimmers oxygenate at a much greater pace, with more oxygen being absorbed into the water because the skimmer is constantly increasing the ponds surface area.
** the preceeding was a cut and paste from an article by Mike Gannon.

I won't pretend to be an expert in pond or koi care, but his explanation simply does not adequately explain his claims. I'll start by saying that I have a bachelors degree in biology with a minor in chemistry, so I may be a bit more eager for a more thorough explanation than the average bear. He may be right, but his explanation as to why he is right is severely lacking.

First of all, a skimmer does not constantly increase a pond's surface area. There is no such thing as virtual surface area. Whether the water is being turned over 100 times an hour or there is no filtration at all, the surface area is the same. He can make the argument that the skimmer brings more highly oxygenated water from the surface (assuming this is where the majority of oxygenation occurs) and circulates it, thus constantly exposing less oxygenated water to the surface. That would make sense.

Secondly, he explains that bubbles don't work because they don't have enough contact time with the water. This is also incorrect. Although each individual bubble isn't in contact with the water for very long, there is a constant stream of bubbles, and oxygenation is occurring at the air-water junction constantly in each little bubble. If we are to assume that his hypothesis that air pumps do very little to oxygenate water, than we have to throw out his explanation. It's not about the time the bubbles are exposed to the water, since the time each individual bubble is exposed is irrelevant if we have a constant stream of bubbles. In fact, fast moving bubbles will increase the rate of oxygenation because fresh air with a higher concentration (albeit very slighlty higher) of oxygen will oxygenate faster than water with a lower concentration of oxygen. So a constant stream of fast moving bubbles is far preferable to slow-moving bubbles (not that we can really control the speed that the bubbles move). What IS important is surface area. I haven't done the math, but I would assume that the surface area of the bubbles is far less than the surface area of the pond surface, which would better explain why they are less effective (if they are, that is).

Keep in mind that when I say that contact time with water isn't important, I'm only saying so because there is a constant stream of bubbles, and thus there is a constant surface area between the water and air regardless of how long each individual bubble is in contact with the water.

I would also like a citation as to where he gets the idea that "It is where the bubbles break up the surface of the water that the oxygenation takes place." Certainly oxygenation takes place here, but to phrase it to mean that this is the only place it takes place in an air pump system is incorrect. Well, it sounds incorrect to me anyhow, at least without a proper reference.

Again, I'm not an expert at anything pond, but I do have a halfway decent grasp on chemistry and biology, and that explanation just doesn't cut it for me. My spidey senses started tingling right away as I was reading his "explanation." I'm also not arguing that skimmers aren't effective at aerating a pond. I don't know enough to dispute or agree with that.

 

[dieselplower]

Trust me, he is trying to sell skimmers and skimmer installs...

 

[Lisaebetten]

Found this and copied here. It is referring to fish tanks and air stones but can be applied to what the bubbles actually do. I don't think it helps in the broad sense of keeping the water temp even especially in a large body of water. Some people keep their systems running all winter and some turn them off and use an air stone and heater if need to keep an ice hole for gas release. This saves much $$$ to turn the pump off while the fish hibernate. I am a newbie as well but I've learned that the fish need it cold to go into hibernation.

It would be fun to do an experiment with a tank and food coloring so see how the water moves with a bubbler.

"Airstones DO increase available oxygen in the water, but not in the way most people think. The process is 2-fold. First bubbles rising from the bottom collect CO2 molecules. When they reach the surface and burst, the CO2 is released along with oxygen inside the bubble provided by the air pump (not from within the tank water). At this point a gas exchange is possible... CO2 out - new oxygen in.
But this can only occur if there is physical agitation on the water surface, which is the second part. A bursting bubble releases a tiny amount of energy which agitates the water molecules providing a tiny ripple. Hundreds of bubbles provide enough agitation to allow a gas exchange to occur (albeit a small one)."
from: guyblom, Yahoo answers 2007.

 

[dieselplower]

It is a proven fact that for the amount of energy spent, an aerator at the bottom of a pond moves far more water than a water pump.

 

[Lisaebetten]

Is one small stone enough for a 1300ish gal pond for the winter? Or will I just have to check to make sure? Does the opening have to been a certain size or will a baseball sized opening be fine? one more question. What is the best locations for this stone in the winter?

 

[dieselplower]

In my opinion a baseball sized hole will work although if your pond is overstocked or has a lot of debris in it going into Winter, I would have to take that back. In my pond I use a water pump and have it about a foot below the surface, shooting up.

 

[max384]

Found this and copied here. It is referring to fish tanks and air stones but can be applied to what the bubbles actually do. I don't think it helps in the broad sense of keeping the water temp even especially in a large body of water. Some people keep their systems running all winter and some turn them off and use an air stone and heater if need to keep an ice hole for gas release. This saves much $$$ to turn the pump off while the fish hibernate. I am a newbie as well but I've learned that the fish need it cold to go into hibernation.

It would be fun to do an experiment with a tank and food coloring so see how the water moves with a bubbler.

"Airstones DO increase available oxygen in the water, but not in the way most people think. The process is 2-fold. First bubbles rising from the bottom collect CO2 molecules. When they reach the surface and burst, the CO2 is released along with oxygen inside the bubble provided by the air pump (not from within the tank water). At this point a gas exchange is possible... CO2 out - new oxygen in.
But this can only occur if there is physical agitation on the water surface, which is the second part. A bursting bubble releases a tiny amount of energy which agitates the water molecules providing a tiny ripple. Hundreds of bubbles provide enough agitation to allow a gas exchange to occur (albeit a small one)."
from: guyblom, Yahoo answers 2007.

The random Yahoo answers user guyblom has a few things incorrect. Firstly, he talks about oxygen being released from bubbles on the surface of the water. That's a load of crap. Air pumps pump regular atmospheric into the water. These pumps don't actually create oxygen. They just bring normal atmospheric air into the tubing and out through an air stone into the water. Secondly, some gas exchange does occur as the bubbles are traveling to the surface of the pond, even if it is only a small amount. Thus, by the time that the bubbles reach the surface, there is actually less oxygen than is in normal atmospheric air (a very very slightly lower concentration, but still...). So, unless a more highly concentrated oxygen mix of bubbles is being pumped into the pond, this point is incorrect.

Also, gas exchange occurs in still water or moving water. However, water which is agitated does facilitate gas exchange more than calm water.

The part about agitating water molecules really cracks me up. The guy is basically trying to do an appeal to authority by using technical-sounding jargon, even though what he says doesn't make complete sense. He talks about agitating water molecules in order to provide for gas exchange. He goes on to describe that the bursting bubble releases energy in order to agitate water molecules. Agitation of molecules means molecular movement. The entire time that the bubbles are rising though the water there is molecular movement, and lots of it. It doesn't make sense that a rising bubble, which is creating water movement (water molecule movement) will not facilitate gas exchange with bubbles full of the same atmospheric air as above (minus whatever gas exchange occurs as the bubbles rise, of course). However, somehow the bubbles creating ripples creates this new water molecule movement, and now suddenly gas exchange takes place? No way.

Again, I'm not pretending to know how effective air stones are. But, I can refute bad and/or poorly explained science. I'd MUCH rather hear anecdotal evidence of how something works or doesn't work than hear a bungled scientific explanation that doesn't make sense, but gets passed around as fact.

 

[JohnHuff]

Let's get down to the basics and look at this logically.

First of all, there's equilibrium. In layman's terms anything with a high concentration will move into something with a low concentration until they are equal. More or less.

So if your water has a low concentration of O2, it will exchange with the atmosphere until it is saturated as per conditions (pressure, temp, etc).

Agitation will simply increase the rate at which this occurs, either way to reach equilibrium. Think of a bottle of soft drink. If you shake it, gas will be released, not the other way around. This is due to physical weakening of the weak temporary bonds, the energy coming from you shaking it.

So think of pond water. If fish is releasing CO2 into the water and you have an excess of it and you agitate it, CO2 will be released. Likewise if you have a scarcity of O2, when you agitate the water, the rate of which exchange into the water occurs will increase.

Regarding the air bubbler:
Compared to the size of a pond, the additional surface area of the bubbles is negligible, so I think we can safely say that if the rate of exchange increases, it isn't gonna be due to gas exchange by the air bubbles inside the pond water.

It could be due to the agitation which disrupts the weak bonds between the water molecules and the dissolved gas molecules. The more energy you put into it the more weak bonds will be disrupted, so this comes down to the amount of energy you put in it.

Lastly, consider what Mike Gannon says. Surface area is important because the greater the surface area, the greater the gas exchange will occur. When doing mental exercises, I always consider the extremes. Think of 100 ft³ of water in a 10 x 10 x 1 flat pond. There's 100 ft² where gas exchange can occur. But consider 100 ft³ of water in a 5 x 5 x 4 column of water. The only exchange will occur in 50 ft² of water. You can see that air will only have 1/2 the opportunity to exchange.

Well, what does breaking the surface tension do? It breaks up the temporary weak bonds between the molecules at the surface and lowers the energy needed for the gas exchange to occur.

Having broken this up into basics, I think we can all see that Mike Gannon isn't just interested in selling skimmers and it makes some sense. I have no dog in this fight as I don't sell skimmers and have neither skimmer nor air pumps in my pond. Trust me, I'm a doctor, as well as a Sir.

 

[JohnHuff]

It is a proven fact that for the amount of energy spent, an aerator at the bottom of a pond moves far more water than a water pump.

Please prove it.

 

[max384]

Let's get down to the basics and look at this logically.

First of all, there's equilibrium. In layman's terms anything with a high concentration will move into something with a low concentration until they are equal. More or less.

So if your water has a low concentration of O2, it will exchange with the atmosphere until it is saturated as per conditions (pressure, temp, etc).

Agitation will simply increase the rate at which this occurs, either way to reach equilibrium. Think of a bottle of soft drink. If you shake it, gas will be released, not the other way around. This is due to physical weakening of the weak temporary bonds, the energy coming from you shaking it.

So think of pond water. If fish is releasing CO2 into the water and you have an excess of it and you agitate it, CO2 will be released. Likewise if you have a scarcity of O2, when you agitate the water, the rate of which exchange into the water occurs will increase.

Regarding the air bubbler:
Compared to the size of a pond, the additional surface area of the bubbles is negligible, so I think we can safely say that if the rate of exchange increases, it isn't gonna be due to gas exchange by the air bubbles inside the pond water.

It could be due to the agitation which disrupts the weak bonds between the water molecules and the dissolved gas molecules. The more energy you put into it the more weak bonds will be disrupted, so this comes down to the amount of energy you put in it.

Lastly, consider what Mike Gannon says. Surface area is important because the greater the surface area, the greater the gas exchange will occur. When doing mental exercises, I always consider the extremes. Think of 100 ft³ of water in a 10 x 10 x 1 flat pond. There's 100 ft² where gas exchange can occur. But consider 100 ft³ of water in a 5 x 5 x 4 column of water. The only exchange will occur in 50 ft² of water. You can see that air will only have 1/2 the opportunity to exchange.

Well, what does breaking the surface tension do? It breaks up the temporary weak bonds between the molecules at the surface and lowers the energy needed for the gas exchange to occur.

Having broken this up into basics, I think we can all see that Mike Gannon isn't just interested in selling skimmers and it makes some sense. I have no dog in this fight as I don't sell skimmers and have neither skimmer nor air pumps in my pond. Trust me, I'm a doctor, as well as a Sir.

But how does a skimmer break the surface tension on the surface of a pond if it maintains a smooth surface, as Mike Gannon purported?

 

[JohnHuff]

But how does a skimmer break the surface tension on the surface of a pond if it maintains a smooth surface, as Mike Gannon purported?

Again, let's consider this as a logical mental exercise.

Looking at it one way, I would say it does not. Bubblers and waterfalls would break surface tension. Anything that breaks the surface of the water would disrupt those temporary bonds called surface tension.

However...

What a skimmer would do is to bring a "new" surface to the top. Where does this "new" surface come from? The water below it. Think of a pond full of marbles instead of water molecules. If you sweep off the top layer of marbles into the skimmer, then a new layer from below will replace it.

If an old layer of surface water is static then it has strong(er) tension because it has no added energy. However, if you sweep this surface layer off and replace it, the new upcoming newer surface layer has more energy by virtue of moving and taking the place of the old surface layer.

So I say in conclusion that the skimmer decreases surface tension by virtue of simple water movement, ie. moving water has less tension than static water.

 

[dieselplower]

John Im not going to waste my time proving anything to you. Not worth it. Tell you what, why dont you disprove me, or, just ask Mike Gannon what he thinks LOL.

 

[dieselplower]

Again, let's consider this as a logical mental exercise.

Looking at it one way, I would say it does not. Bubblers and waterfalls would break surface tension. Anything that breaks the surface of the water would disrupt those temporary bonds called surface tension.

However...

What a skimmer would do is to bring a "new" surface to the top. Where does this "new" surface come from? The water below it. Think of a pond full of marbles instead of water molecules. If you sweep off the top layer of marbles into the skimmer, then a new layer from below will replace it.

If an old layer of surface water is static then it has strong(er) tension because it has no added energy. However, if you sweep this surface layer off and replace it, the new upcoming newer surface layer has more energy by virtue of moving and taking the place of the old surface layer.

So I say in conclusion that the skimmer decreases surface tension by virtue of simple water movement, ie. moving water has less tension than static water.

But an aerator would clearly cause more surface movement and at much lower cost than a pump in a skimmer.

 

[JohnHuff]

But an aerator would clearly cause more surface movement and at much lower cost than a pump in a skimmer.

This is something which simply saying it isn't proof. You'd have to look at the efficiency of the particular device, usage of power and a way to measure movement.