Air Stones....

[snazy]

Noisy, and Ugly, I'd rather just get a decent LPH filter and use that to disturb the surface.

Try that on my small 7 gallon tank, I would have to throw the fish out to do so.
I think whether you use an air pump or power head additionally, or more powerful filter just depends on the size of tank,current setup, personal preference and requirements of the tank. I certainly don't need anything else in my small tank, as the filter is circulating the water about 17 times an hour(400L/H) and the outflow is a long srpay bar splashing this into the surface, but with a less powerful filter which most tanks come with, I don't see this being the case.

 

[Bignose]

I did understand that the majority of oxygen is exchanged at the surface area of the tank. But as you also confirm yourself, the air pumps do aerate the water by being "helpful" in creating more surface area.
So what is the big discussion here for? There was no need to dig into another threads about how exactly air pumps aerate the water, the point is they do, one way or another, and they have been doing so for more than 100 years of fishkeeping. So the answer to one of this thread's initial questions, whether an air pump aerates a tank or not, is simply Yes. Isn't this what all of us here were saying? Well, except one person maybe that said they are for decoration and aesthetics only.

The problem is that the poll question is ill-posed at the very least. The only choices are "Good" or "Bad" or "I don't know". No metric or definition of good or bad is given.

Do they circulate tank water? Yes, and most people would think that good. But not always, some species prefer very still waters, in that case it is bad.

Do they provide much oxygenation? No, and most people would probably call that bad. But they do provide other things, like decoration and entertainment, etc.

That is what the large discussion has tended toward -- trying to find a more objective measure of the words "Good" and "Bad". Of which one of the measures is how much oxygenation they actually provide.

Really, it all comes down to a personal choice. There are many ways of successfully keeping fish. Clearly, an airstone is not necessary, many people keep tanks without one. But, they generally don't cause any harm, so it becomes a personal choice.

 

[Ace Of Spades]

Noisy, and Ugly, I'd rather just get a decent LPH filter and use that to disturb the surface.

Try that on my small 7 gallon tank, I would have to throw the fish out to do so.

That's not a tank, that's a drinking cup.

 

[DevotedToDiscus]

As stated "There are many ways to successful fish keeping" And one of the major factors to successful fish keeping is having confidence in what you are doing. So IMO, if running and air stone(irrelevant of the science behind it) gives you more confidence, then it is a good thing.

I am amazed at what a storm such an innocent question has kicked up!

 

[snazy]

That's not a tank, that's a drinking cup.

Ha, ha. That was funny. It may be a drinking cup, but it is just fine to raise guppy fry

 

[snazy]

But look, take a bubble of 0.5 mm radius. This will have a surface area of 3.1416 * 10^-6 m^2. A 20 gallon tall tank has dimensions of 24 in wide * 13 in deep. This is equal to 0.20129 m^2 of area. Dividing the two, the surface is equal to over 64,000 0.5 mm bubbles. There is no airstone that puts out 64,000 bubbles. And, the surface is always refreshed, whereas the bubbles -- if there was time to exchange much gas (which there isn't since they get to the top very quickly) -- would be constantly depleted.

I actually have just one question about this formula. Where is the time in it?
I mean you are saying that a tank needs 64 000 bubbles to aerate a 20 gallon tank. Do you mean 64 000 bubbles at once? Then if there is such an air pump in reality, it would oxygenate a tank instantly and you can just switch it on once a day for a second or two
By the way, can you calculate how many air bubbles of 0.5 mm radius can a certain air pump produce in certain interval of time, let's say 24 hours?



I took the text below out of Wiki, which I know is not a trustworthy source completely, but the funny part is that EPA, U.S. Environmental Protection Agency is quoted in it. And also the below type of air pump outputs 30 to 50 thousand bubbles a second, which aerates an entire pond. However, your claim is that you need 64 thousand bubbles to aerate some 20 gallon drinking cup. My guess is you did not take time into the calculations.

Fine bubble aeration is an efficient way to transfer oxygen to a pond. A compressor on shore pumps air through a hose, which is connected to an underwater aeration unit. Attached to the unit are a number of diffusers. These diffusers come in the shape of discs, plates, tubes or hoses constructed from glass-bonded silica, porous ceramic plastic, or perforated membranes made from EPDM (ethylene propylene diene Monomer) rubber.[2] With EPDM rubber units, there are approximately eight thousand holes per disk through which air is diffused. Air pumped through the diffuser membranes is released into the water at a rate of roughly 30-50 thousand bubbles per second. These bubbles are known as fine bubbles. The EPA defines a fine bubble as anything smaller than 2mm in diameter.[5] This type of aeration has a very high oxygen transfer efficiency (OTE), sometimes as high as 15 pounds of oxygen / (horsepower)hour.[2] On average, diffused pond aeration diffuses approximately 2-4 cfm (cubic feet of air per minute), but some operate at levels as low as 1 cfm or as high as 10 cfm.

By releasing millions of fine bubbles instead of fewer coarse bubbles, fine bubble diffused aeration is able to maximize the surface area of the bubbles and thus transfer more oxygen to the pond per bubble. Additionally, smaller bubbles take more time to reach the surface so not only is the surface area maximized but so are the number of seconds each bubble spends in the water, allowing it more time to transfer oxygen to the water. As a general rule, smaller bubbles and a deeper release point will generate a greater oxygen transfer rate

 

[Noahs ark6]

Should i use an airstone during the night in a planted tank?

 

[Bignose]

But look, take a bubble of 0.5 mm radius. This will have a surface area of 3.1416 * 10^-6 m^2. A 20 gallon tall tank has dimensions of 24 in wide * 13 in deep. This is equal to 0.20129 m^2 of area. Dividing the two, the surface is equal to over 64,000 0.5 mm bubbles. There is no airstone that puts out 64,000 bubbles. And, the surface is always refreshed, whereas the bubbles -- if there was time to exchange much gas (which there isn't since they get to the top very quickly) -- would be constantly depleted.

I actually have just one question about this formula. Where is the time in it?
I mean you are saying that a tank needs 64 000 bubbles to aerate a 20 gallon tank. Do you mean 64 000 bubbles at once? Then if there is such an air pump in reality, it would oxygenate a tank instantly and you can just switch it on once a day for a second or two
By the way, can you calculate how many air bubbles of 0.5 mm radius can a certain air pump produce in certain interval of time, let's say 24 hours?

There is no time because it isn't important! The comparison is meant to be at any instant in time. All it is is a comparison between areas. If you took the top of a tank, cut up all the surface area it encompasses, and stitched them together into bubbles, it would make over 64,000 0.5 mm bubbles. So that says that the top of the tank is equal to 64,000 bubbles' surface area.

And, since the amount of mass transfer is directly proportional to the amount of surface area, in order to equal the amount of mass transfer from the surface of the tank, at any instant in time, there would have to be 64,000+ bubbles in the water. No airstone does that.

Or, if you prefer, to equal 1 days worth of mass transfer from the surface, the airstone would have to run at a rate in which there is always 64,000 bubbles in the tank at every instant during 1 day.

And no, I can't calculate how many air bubbles an airstone makes -- too many variables. I would estimate most airstones to have a few hundred bubbles in the water at any moment in time.

 

[ian]

Should i use an airstone during the night in a planted tank?

Some people use them if running really high amount of C02...I have never seen the point in it personally. Raising your outlet will normally do the trick. Theres no need at all if your not running pressurised C02.

 

[snazy]

There is no time because it isn't important! The comparison is meant to be at any instant in time. All it is is a comparison between areas. If you took the top of a tank, cut up all the surface area it encompasses, and stitched them together into bubbles, it would make over 64,000 0.5 mm bubbles. So that says that the top of the tank is equal to 64,000 bubbles' surface area.

And, since the amount of mass transfer is directly proportional to the amount of surface area, in order to equal the amount of mass transfer from the surface of the tank, at any instant in time, there would have to be 64,000+ bubbles in the water. No airstone does that.

Actually, in the the example given in my previous post, that pond air pump produces only 30 000 to 50 000 thousand bubbles a second. It claims that this type of aeration produces 15 pounds of oxygen / (horsepower)hour.
So you reckon that even that air pump would not be enough for a 20 gallon tank?

 

[Bignose]

There is no time because it isn't important! The comparison is meant to be at any instant in time. All it is is a comparison between areas. If you took the top of a tank, cut up all the surface area it encompasses, and stitched them together into bubbles, it would make over 64,000 0.5 mm bubbles. So that says that the top of the tank is equal to 64,000 bubbles' surface area.

And, since the amount of mass transfer is directly proportional to the amount of surface area, in order to equal the amount of mass transfer from the surface of the tank, at any instant in time, there would have to be 64,000+ bubbles in the water. No airstone does that.

Actually, in the the example given in my previous post, that pond air pump produces only 30 000 to 50 000 thousand bubbles a second. It claims that this type of aeration produces 15 pounds of oxygen / (horsepower)hour.
So you reckon that even that air pump would not be enough for a 20 gallon tank?

Bubbles of what size? A bubble half the size of my example one would have 1/4 the surface area. 30-50,000 bubbles alone is not enough information.

Furthermore, the units of 15 pounds (mass I assume) per horsepower*hour don't make much sense. I don't understand that unit of power (horsepower) in the numerator at all.

But, my estimate says that 30-50,000 0.5 mm radius bubbles would still be less surface area than the top of the tank. Even with that large number of bubbles, there would be more mass transfer through the tank surface than the bubbles.

 

[snazy]

Bubbles of what size? A bubble half the size of my example one would have 1/4 the surface area. 30-50,000 bubbles alone is not enough information.

According to the article, the bubbles are known as fine bubbles, defined by EPA as smaller than 2mm in diameter.

Furthermore, the units of 15 pounds (mass I assume) per horsepower*hour don't make much sense. I don't understand that unit of power (horsepower) in the numerator at all.

I found the following article explaining the above measure:

There are two ways of describing aerator performance. The standard oxygen transfer rate (SOTR) is the amount of oxygen added to water in 1 hour under a standard set of conditions. The units of SOTR are pounds O2/hour, which can be multiplied by 0.45 to derive the metric equivalent in kg O2/hour. Standard aeration efficiency (SAE) is the standard oxygen transfer rate divided by the power requirement in horsepower (hp). Units of SAE are pounds O2/hp·hour, which can be multiplied by 0.61 to derive SAE in metric units of kg O2/kW·hour. Boyd (1998) thoroughly describes aerator performance testing and how to interpret and use SOTR and SAE values.

Aerators transfer less oxygen under pond conditions than under the standard conditions of aerator performance tests, so SOTR and SAE values are best used to compare similar styles of aerators as an aid in selecting equipment to purchase rather than as design criteria for pond use. Also, small differences in SOTR and SAE values are not meaningful because test conditions may vary and affect results. Boyd and Ahmad (1987) compiled SOTR and SAE values for a variety of aerators used in pond aquaculture.


According to the above, 15 pounds O2/Horsepower.Hour is 9.15 kg O2/Kw.hour

Actually, the whole article is very insteresting. It explains how to calculate dissolved oxygen, which apparently depends on other factors than surface area/volume ratio as per your example, and the full formula is there. Here it is:

http/www.thefishsite.com/articles/169/pond-aeration

 

[raptorrex]

Noisy, and Ugly, I'd rather just get a decent LPH filter and use that to disturb the surface.

Try that on my small 7 gallon tank, I would have to throw the fish out to do so.
I think whether you use an air pump or power head additionally, or more powerful filter just depends on the size of tank,current setup, personal preference and requirements of the tank. I certainly don't need anything else in my small tank, as the filter is circulating the water about 17 times an hour(400L/H) and the outflow is a long srpay bar splashing this into the surface, but with a less powerful filter which most tanks come with, I don't see this being the case.

this does not make sense. 5x or 25x the same proportion of water will be moved in any size tank. so the flow will no be higher in a smaller tank..

as for the thread subject. the science is clear. though you seem to resist it.

 

[snazy]

Noisy, and Ugly, I'd rather just get a decent LPH filter and use that to disturb the surface.

Try that on my small 7 gallon tank, I would have to throw the fish out to do so.
I think whether you use an air pump or power head additionally, or more powerful filter just depends on the size of tank,current setup, personal preference and requirements of the tank. I certainly don't need anything else in my small tank, as the filter is circulating the water about 17 times an hour(400L/H) and the outflow is a long srpay bar splashing this into the surface, but with a less powerful filter which most tanks come with, I don't see this being the case.

this does not make sense. 5x or 25x the same proportion of water will be moved in any size tank. so the flow will no be higher in a smaller tank..

as for the thread subject. the science is clear. though you seem to resist it.

The power head in the 7 gallon tank is as big as one of the filter power heads in the 30 gallon tank. The small tank has a spray bar all along the back of the surface which agitates all the surface and is quite strong. The filters in my 30 gallon do not come with a spray bar, one is a hood filter, the other is Fluval U4 and they don't do too much at the surface to be honest, maybe from one side mostly. Probably with a different filter outflow, it could be a different story. At the moment I can't rearrange the current filters to get better movement at the top, so hence the air bubbler.

As for the science, I must be reading a different science than you do obviously. It just seems that it doesn't suit your opinion, and you prefer to turn this into a personal insult, to distract from the main subject.

 

[Bignose]

As for the science, I must be reading a different science than you do obviously. It just seems that it doesn't suit your opinion, and you prefer to turn this into a personal insult, to distract from the main subject.

snazy, no one has made any personal insults. Members of this forum can disagree with one another, but we don't tolerate personal attacks or people being disagreeable.