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 L# Planted Aquaria
  L# Air Exchange, CO2 and Oxygen
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SubscribeAir Exchange, CO2 and Oxygen
Callatya
 
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WHY are airstones considered a nono if one does not have CO2 injection?

does it not also bring in CO2 as well as oxygen?

I mean, its not really an oxygen stone, its an air stone, and air is made of many gases, including oxygen and CO2.


If someone is actively injecting CO2, i do see the problem, but if someone is not, wouldn't surface agitation actually benefit the tank with CO2? surely the plants consume CO2 and then leave the water depleated, and providing gas exchange would enable a fresh supply??


PLEASE someone give me some scientific explanation as to why airstones do or do not help.




I am not accepting regurgitated internet waffle, so get your teacher hats on and explain from scratch, and back it up!
I would like to hear personal experience though.





For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett

Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Report 
bensaf
 
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Ok Cal, I'll take a bite of this one. Don't expect much in the way of scientific explanation though.

does it not also bring in CO2 as well as oxygen?

I mean, its not really an oxygen stone, its an air stone, and air is made of many gases, including oxygen and CO2.

You're quite right, it's not like airstones are connected to an oxygen bottle. Yes, it will bring in some Co2. But it will drive off more co2 then it takes in. Which is greater the Co2 content of aquarium water or the co2 content in the air we breathe ? Maybe one of the "scientists" you beseeched will have the numbers !

surely the plants consume CO2 and then leave the water depleated, and providing gas exchange would enable a fresh supply??

Well the plants only consume Co2 during the day , at night they consume O2 and exhale Co2. Plus the fish are constantly exhaling Co2. There is always a constant supply of Co2 and in greater quantities then an airstone can bring in.

WHY are airstones considered a nono if one does not have CO2 injection?

Well to answer your question I would consider airstones worthless in a planted tank. But not for reasons of retaining Co2. An average tank with no Co2 supplementation has a Co2 content of about 3-4ppm. Running an airstone would probably reduce that to 2ppm. That is not going to make a blind bit of difference to the plants considering you need levels of about 15ppm and above to see any noticable improvement in growth.
I just think airstones are pointless in a planted tank. If the plants are growing at all they are giving out oxygen is sufficient quantity to keep the tank well oxygenated. In that case the airstone serves no purpose other then decoration. Never understood the decorative qualities of a wall of bubbles in a planted tank

Last edited by bensaf at 08-Feb-2005 01:58


Some days you're the pigeon and some days you're the statue.

Remember that age and treachery will always triumph over youth and ability.
Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
Callatya
 
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That sounds plausable.

If the tank is just plants, no fish to produce CO2, would the water still have more CO2 in it than what the air could provide?

I suppose i don't quite see how it gets there in the first place without the fish respiring. And how much can one fish produce? is there a certain stocking level youy need for good CO2 production?


And i agree, very few cases where bubbles are decorative.


I'm sorry, i didn't mean to sound mean or elitist, i'm just sick and tired of not understanding why, and nobody being able to tell me

For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett

Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
Shannen
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Calla,
I'm not sure on the exact exchange, but if the tank had no fish and only plants. It would still produce CO2. At night plants revers their respiration and give off CO2.

HTH
Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
bensaf
 
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Cal,

I didn't think you sounded the least bit mean or elitist. I know what you mean. Sometimes the only answers received are repeated snatches that were read somewhere without the quoter fully understanding what they are repeating. When you ask for clarification there's suddenly silence.
Do it myself sometimes


Some days you're the pigeon and some days you're the statue.

Remember that age and treachery will always triumph over youth and ability.
Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
Callatya
 
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OK, so the CO2 gets into the water by plants respiring and fish respiring. (does it folow, the more plants/fish, the more CO2, but the more plants, the higher the requirement?)

And for some reason (loose molecular bonds/no molecular bonds?) the agitation of the water jiggles more out than it lets in.

Am i getting this?

For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett

Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
FRANK
 
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Hi,
Generally speaking, the normal CO2 saturation in water
is about 5mg/l. When we inject CO2, we supersaturate the
water and bring the saturation closer to 30mg/l.
We find that plants grow faster, stronger, and more lushly
with a CO2 saturation between 15mg/l and 30mg/l. There
has been some discussion that over 30mg/l can cause fish
stress, particularly with the lights out when both fish
and plants use O2.
We rely on surface tension to retain most of that.
Airstones break the surface tension and agitate the
water allowing the the disolved gas to attempt to reach
equilibrium.

With a typical DIY system, there are no controls on the
rate of production of CO2 or the flow of CO2. You choose
the container (generally a 2 liter, thin, plastic, pop
bottle) pour in the water, yeast, and sugar, shake gently,
and cap. The gas starts immediately and rapidly increases
as the yeast and sugar react. Over time, the surge of
CO2 reduces as the agents are used up (converted to alcohol)
and then the bottle is replaced with another and a fresh
mix. This produces a surge of CO2, followed by a drop off,
followed by another surge, etc. Because of the components,
and the system design, you can't shut off production of
the gas, nor control its flow. The usual results of trying
to do this is and explosion (the plastic bottle ruptures)
or leaks from various seals.
Not using an airstone, and controlling surface agitation
is particularly important because of the lack of control.
You need to conserve, use what is generated.

With a bottled system however, you can use airstones,
if necessary, or spray bars, and because you have
control of the gas and compaired to a DIY system a nearly
unlimited quantity of gas, you can always increase the
rate of injection to maintain a given overall saturation.
Ie, go from one bubble/sec to two or three or more/sec.

Most folks with lush jungles, rarely use airstones at all.
Some at night when they turn off the injection. Most will
use power heads, operating, below the surface, primarely
to provide circulating currents within the tank to
distribute nutrients, and temperature, evenly within the
tank.

HTH...
Frank


Last edited by FRANK at 08-Feb-2005 05:10

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Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
Callatya
 
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female australia au-newsouthwales
So adding an airstone to non-supersaturated water will reduce levels from 5mg/l to something less?

For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett

Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
FRANK
 
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Hi Calla
No, Adding an airstone would not affect the CO2 equlibrium.
the Co2 saturation would remain around 5mg/l. However,
it would increase the O2 saturation, slightly tho.

Frank


Last edited by FRANK at 08-Feb-2005 14:43

-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--
Post InfoPosted 26-Jan-2006 11:43Profile PM Edit Delete Report 
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