Air bubbles

[IITUFFTOBEATII]

does anyone know of a free site where I might be able to host these files so that I can post a link for them to be downloaded? I would email the files to everyone if they asked, but this would make it easier.

 

[Nova 8]

Im not convienced by reading the two word documents. I read both of them and by what I've read you haven't actually tested this on an aqurium with filters and fish. All that is done is a beaker of water is left on a counter with a bubble stone, and then with out and when the bubbles are in the beaker oxygen returns faster (what a surprise), there are also to many variables in the test and in an aquarium, the main one being the pouring of the water.
This may not tranfer with the same results to an up and running aquarium (have you tried this?). Also what shape beaker were you using, you have to remember that an aqurium, generally, has the same size top as it does bottom giving a fairly large surface area. If the beakers your during this test were either taperred at the neck or quite tall this would change the results to what it would be in an aquarium due to the small surface area.
If you have evidence to support that these results would transfer to an aquarium, and also be more effective then a wavemaker. Point me towards it, otherwise we are going to have to agree to disagree.

 

[greenterra]

I read it and can see how you got those answers but I do agree with Nova 8 in saying that there are other variables.You can't compare a beaker to a 180 gal tank.You did the test as
1 beaker left still
1 beaker slow bubbler
1 beaker fast stirred
1 beaker fast bubbler

I wan't to know how did you stir it.If you did it by hand then I can see the bubbler would win without a doubt.My point is though if you got a mini blender it would leave the bubbler for dead.

I attached a link about the designs they came up with in bankok to raise the oxygen levels in the rivers.If you read it it shows how much oxgen per horsepower of energy each system creates.
The Chaipattana Aerator model RX5 (Chaipattana Air-jet) further down the page creates equivalent to 2 kilograms of oxygen per horsepower per hour using an agitating motion.It leaves the other designs listed for dead.

After reading this site aswell I am not convced now that bubblers(air stones) are the fastest or most efficient.http://www.rid.go.th/eng/Water%20Treatment%20Work.htm

 

[Miguel]

Wow! We have some serious "enginnering " in here!! I have always had air stones in the tanks nad power heads cutting through the surface ( since I ,a dmittedly wrongly, thought this was needed not only to promote circulation and oxigenation, BUT also to break the tension )..

And I will continue like that, I hope forewer.

Now, Nova and Greenterra, what would the variables you refer to ( between a big tank and a vial where the experiment was done ) provoke in terms of ascertaining the ratio of dissolved oxygen?

 

[Nova 8]

Things like; (I am no sciencetist, and as put by tufftobeat, I am a "hobbiest" so what I say may be incorrect in science "terms")

-Surface area to water volumn ratio

-Size, the bubbles in the beaker would probably fill most of the water, in MFkers aquarium it would take 100's of airstones and pumps to get the same effect

-Shape

-Exact ammount of air getting pumped in per min (not just fast and slow has to be levels ie 1 pounds per minute)

-Water and Air tempreture

-The water used was pure, not aquarium water with 'other' matter in it

-No filters for water movement as in an aquarium, with and without bubbles

-A Human moving the beaker is a varible in itself

-FISH, Plants, Rock, Substrate, Driftwood and any thing else in an aquarium that doesn't exist in ideal environments used for tests can have a effect aswell


I'm sure theres more, just as I'm sure that some what I said is probably incorrect.

There is no way that tufftobeat can say the result would be exactly the same if done in an aquarium unless testing it, if he wishes to prove me wrong he is welcome to come to my house pick up my 220 gallon tank and give it a shake:j/k: .

 

[Miguel]

Nova, I see where you are coming from. And the variables you highlighted totally make sense to me. But something must be missing in here, because I am sure that a water treatment facility of the magnitude ITuffbeat mentions does not base its conclusions on vial tests, only.

I will stick to my method, but one mistake i lived with for 30 years has been "corrected" by this thread ( the non impact of surface tension on gas exchange ).

 

[greenterra]

Now, Nova and Greenterra, what would the variables you refer to ( between a big tank and a vial where the experiment was done ) provoke in terms of ascertaining the ratio of dissolved oxygen?

I say that because to get an accurate test you would have to put it into some scale compared to an aquarium.Take the airstone in a beaker for example.One would think the bubbles would take up pretty much the whole water surface in the beaker.Now I for one do not want to turn my tank into a spa bath.For that reason I think the test should be performed on a larger scale to somewhat resemble the conditions in an aquarium.That is why I liked the link I posted as it is performed on a huge scale giving a somewhat more accurate picture.The fact that they actually rate as oxygen per kilogram for 1 horsepower per hour gives us better idea of what is most efficient.In their government studies their injected bubbler systems were some of the least efficient.

 

[Nova 8]

Nova, I see where you are coming from. And the variables you highlighted totally make sense to me. But something must be missing in here, because I am sure that a water treatment facility of the magnitude ITuffbeat mentions does not base its conclusions on vial tests, only.

I will stick to my method, but one mistake i lived with for 30 years has been "corrected" by this thread ( the non impact of surface tension on gas exchange ).

Ever thought they go with bubbles as its more cost effective compared with a wakemaker of somesort, even though it may be less effective. The wavemaker would need more electricity, maintiance and room whereas for bubbles you only need a pump and hose. Which will use less electricity and room and require less money to setup and future maintiance. But in an aquarium both are fairly cheap. It cost me roughly $40AUD for a large pump, hoses, suckers and airstone whereas it is $50AUD for a good, powerful filter which also help keep the water clean.

 

[IITUFFTOBEATII]

Ever thought they go with bubbles as its more cost effective compared with a wakemaker of somesort, even though it may be less effective. The wavemaker would need more electricity, maintiance and room whereas for bubbles you only need a pump and hose. Which will use less electricity and room and require less money to setup and future maintiance. But in an aquarium both are fairly cheap. It cost me roughly $40AUD for a large pump, hoses, suckers and airstone whereas it is $50AUD for a good, powerful filter which also help keep the water clean.

I dont even know where to begin and I have to go into work in just a few minutes......

The test was done with 500 ml beakers, no taper. You are correct that it has very little surface area by itself.

You are missing the point entirely. Dissolved Oxygen CONCENTRATION is independent of volume. If the same experiment had been done on a larger scale, say 1000, or 1 million gallons, and the same proportion of bubbles was used the results would be the same.

I have not personally tested this on my aquarium because it is not necessary in my case. Most fish will be healthy at DO concentrations above 5.5 mg/l, it takes more waste than my fish can produce to drop the DO below that level. Along those lines, and similar to what I told you in my email Nova; The alternate methods that the rest of you swear by are more than sufficient, the results that I pointed out to you also showed that. I never said that using powerheads and the like didnt work, I simply stated that using air bubbles was superior. I do know that what I have said before will work regardless of water volume, it is proven every day not 20 miles from me in the Elk Grove Ca wastewater treatment plant. There is more waste treated through that plant in one day than every fishkeeper combined on MFK sees in a year. So yes the experiment uses a small volume of water, but the principles apply to much larger volumes in the exact same way, whether its 180 gallons or 180 million gallons.

You are mistaken to think that aerating water through bubbling is cheaper than surface agitation, it is actually quite a bit more expensive, and plants nearing capacity often use pure oxygen instead of plain air. Both systems, aeration and mechanically moving the water most likely could be run using the same size motors, the aeration systems are much more complex, require more in design and construction costs, and cost more to maintain

Sorry I must leave now. I will return this evening to continue this conversation.

One final note though, this experiment is done in 18 different sessions every semester at CSUS alone, this is likely true at other universities around the world that have enivironmental engineering classes/labs. The purpose of which is to understand gas transfer and also to show which methods of aeration produce the best results. It is unfortunate that you fail to see the proof, I do however have the privelage of having knowledgable people to explain it to me and answer every question I throw out them with crystal clarity

 

[Koji]

The finer the bubbles produced by the airstone and the longer they're in the water, the more effective the gas exchange will be.