# Is there plenty of oxygen for fish when plants a pearling?



## Darkblade48 (Jan 4, 2008)

If you are sure that the plants are pearling and not "false" pearling (also known as streaming, which occurs when the plant is damaged and gases escape), then yes, it would indicate that the water is fully saturated with oxygen.


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## miogpsrocks (Sep 3, 2015)

Darkblade48 said:


> If you are sure that the plants are pearling and not "false" pearling (also known as streaming, which occurs when the plant is damaged and gases escape), then yes, it would indicate that the water is fully saturated with oxygen.


I did not even know there was such a thing. I guess I should check with the light off and use a flashlight or something to see if the bubbles continue. What other way to tell if they are false pearling? 

I got the plants at Petco and they are not that old so I am not sure how much damage is on the plant. 

Thanks.


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## jrill (Nov 20, 2013)

I have never heard of anyone ever report pearling from using liquid co2.


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## BBradbury (Nov 8, 2010)

*O2 Level for Fish*

Hello mio...

Oxygen is a plant byproduct. The plants take in light, carbon dioxide (CO2) and water and the result is oxygen. Your filter system also mixes O2 from the surrounding air into the tank water by agitating the surface. Adding a plastic tube to the tank attached to an air pump will do the same thing as the filter by moving the water surface and mixing O2 into the tank water.

Plants pearl when there's too much O2 in the water, like after a large water change. It's their way of removing extra oxygen. If your plants are pearling, there's plenty of O2 in the tank water

B


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## Darkblade48 (Jan 4, 2008)

miogpsrocks said:


> I did not even know there was such a thing. I guess I should check with the light off and use a flashlight or something to see if the bubbles continue. What other way to tell if they are false pearling?
> 
> I got the plants at Petco and they are not that old so I am not sure how much damage is on the plant.
> 
> Thanks.


False pearling generally appears as a constant/steady stream of bubbles. 

Pearling will appear as bubbles accumulating on the surface of the leaf, much like how there will be some bubbles that stick to a side of a glass when you pour in a carbonated beverage.



jrill said:


> I have never heard of anyone ever report pearling from using liquid co2.


This is also why I suspect it is not real pearling and simply due to some damage to the plant.


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## lksdrinker (Feb 12, 2014)

False pearling is also quite common after a water change. There are a lot of dissolved gasses in most tap water and this results in tiny bubbles on most surfaces after a water change.


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## PerfectDepth (Dec 3, 2014)

Darkblade48 said:


> If you are sure that the plants are pearling and not "false" pearling (also known as streaming, which occurs when the plant is damaged and gases escape), then yes, it would indicate that the water is fully saturated with oxygen.


This is something I've wondered about. Given that O2 doesn't dissolve as quickly as say, CO2, for example, I wonder if the tank water is actually saturated with oxygen, or is it just being produced more quickly than it is able to dissolve?


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## flight50 (Apr 17, 2012)

Sounds like plant damage to me as well. Last time I checked, Petco has very poor conditioned plants. Petsmart on the other hand has taken plant care out of the hands of the people that work there. Great move. I am sure we have a case of false pearling though. Bubbles don't really come out like the OP describes when the plant pearls. They accumulate on the leaves and pretty much stay put. When I hear bubbles coming out and needing a flash light, it sounds like bubble are continuously streaming to the surface. Pearling bubbles don't rise to escape like streaming bubble from plant damage.


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## houseofcards (Mar 21, 2009)

PerfectDepth said:


> This is something I've wondered about. Given that O2 doesn't dissolve as quickly as say, CO2, for example, I wonder if the tank water is actually saturated with oxygen, or is it just being produced more quickly than it is able to dissolve?


That was always my view on pearling. The plant is producing O2 at too quick a pace to be dissolved, although I guess 'pearling' can occur if the water is saturated as well. 

If you have pearling in a thinly-planted setup, then I would reason to believe it's that particular plant that is producing O2 very quickly.


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## Willcooper (May 31, 2015)

I have had pearling occur in every condition; with co2 without co2 with liquid carbon and without. Pearling will occur at a much higher rate with co2 and optimal light and nutrients. If you look at the plant and see a stream of bubbles coming out of a "broken area" that is false pearling. I have had all my plants pearl like crazy without any co2. It is simply the plants producing o2 at high high rate which usually means conditions are favorable, at least until the algae comes if there isn't enough co2 in the tank.


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## plantetra (May 17, 2014)

This is good info. So do you mean that if you are limited by light and not CO2 or fert, there wont be any pearling?


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## WaterLife (Jul 1, 2015)

^

I thought pearling only occurred when the oxygen solubility limits of the water volume have been reached, and thus bubbles of o2 are formed, but do not dissolve because the threshold of o2 has already been reached.

Essentially there is more o2 (being produced) in the water than it can hold.


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## essabee (Oct 7, 2006)

@Darkblade48, 

This "false" pearling/streaming that you talk about - would you care to let us know what sort of gasses are being let out by the plant and how are they produced by the plant?
@jrill, 

Why would not "liquid co2" cause pearling - the source of CO2 would have nothing to do with pearling which is a result of high rate of photosynthesis?


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## Argus (May 22, 2013)

essabee said:


> @Darkblade48,
> 
> This "false" pearling/streaming that you talk about - would you care to let us know what sort of gasses are being let out by the plant and how are they produced by the plant?


Abby is keeping Major Masspec busy, so I don't know what gasses are being released, but I've seen streams of bubble coming from cut stems. 



> @jrill,
> 
> Why would not "liquid co2" cause pearling - the source of CO2 would have nothing to do with pearling which is a result of high rate of photosynthesis?


My understanding is that "liquid CO2" provides carbon to the plants in a different form. It does not provide actual CO2. Plants are able to utilize carbon from CO2 more efficiently than from liquid carbon sources. Otherwise, there wouldn't be any point to having expensive pressurised CO2 systems. It would be much easier and cheaper to use liquid.


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## WaterLife (Jul 1, 2015)

@Argus

Yeah, I've had cut stems release bubbles out as well, I have no idea what gasses are released.

But the point about liquid carbon and pearling is, even though glute is not co2, it still increases the rate of photosynthesis (although that carbon source is not as easily utilized by the plants) and so the plants could potentially produce more oxygen than the water can hold and so o2 bubbles/pearling, technically should be able to appear.
Hence he is saying pearling is more so from high photosynthesis rates rather than sources of carbon.

I have no experience with using liquid carbon (excel, metricide 14, glute), but theoretically it should be able to incite pearling, but I cannot say for sure it pearling results are seen with practical dosage (achievable probably in higher than normal dosing, but in recommended dosage, I haven't heard many say that they have had pearling using liquid carbon). But then again, no experience with it and haven't heard too many testimonies, so it very well might be able to at _ typical _ dosages.


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## Argus (May 22, 2013)

WaterLife said:


> @Argus
> 
> Yeah, I've had cut stems release bubbles out as well, I have no idea what gasses are released.
> 
> ...


While possible, I think it much less likely to have pearling with liquid carbon sources than CO2 gas. Since liquid is a less efficient source of carbon it doesn't support as high light levels as CO2. Photosysthesis levels cannot be as high with liquid as with CO2.

I'm not so sure about this point, but I think that when there is a lot of dissolved CO2 in the water, there is less room for oxygen. So oxygen saturation levels are reached earlier. 

For these reasons you are less likely to see pearling with Excel than you are with pressurized CO2.


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## WaterLife (Jul 1, 2015)

@Argus
From what I have read, co2 soluble levels and o2 soluble levels are independent of one another, meaning they won't displace each other, they will simply "expel/gas off" out of the water if in excess. The water will only hold a certain soluble limit/threshold of those gases.

But that might just be based on typical atmospheric (pretty sure that's not the right word I'm looking for) conditions and things might be different when those gasses are being pressure injected and then it might be possible to "drive off" other gases to make more room for the gas that is being pressurized-injected in excess to inject in excess of soluble limits. Not completely sure on that as the gas being injected is pressurized, but the water itself isn't really in a seal pressurized box, but clearly gassing out fish is possible so excess amounts seems possible, but why wouldn't it off gas or pearl if in excess just like o2 pearls (wouldn't the water naturally try to return to the regular soluble limits by expelling the gasses in excess?)? Hopefully someone can chime in and enlighten me.

Well what I am getting at is maybe pressurized co2 system running overly high PSI's (not really sure how much pressure would be needed) can drive out o2 (and probably other gases), but I am pretty sure under typical planted tank co2 pressures, it isn't high enough to displace o2 levels nor lower o2 saturation limits.

So all in all, the excel vs co2, I just don't think practical dosage amounts of excel give the plants enough "umph" to produce oxygen (to the point of reaching saturation limits/pearling) nearly as fast as pressurized co2 and not fast enough to reach o2 saturation limits if there are enough fish present intaking the o2, but I assume may be possible to have pearling using excel if either dosed heavily or if there is no large amount of o2 intakers (fish, inverts, even bacteria, microorganisms) so o2 levels can build up and reach pearling status easier.

Excel is a inferior carbon source, but theoretically I believe it could support just as high light levels as pressurized co2, but the dosage would probably not be practical.
I know pressurized co2 is better, but I am just theoretically speaking whether or not pearling is achievable by way of liquid carbon dosing. *heh, I'm repeating myself aren't I, oh well I already typed it...*





But anyways, back on topic for the OP's question.

As long as the amount of co2 isn't too high, then yes pearling plants means the water is highly saturated with oxygen.
However you might have heard of fish dying in co2 injected tanks even though there is plenty of oxygen.
That reason fish die may be from too high levels of co2 and not because of lack of oxygen, it is because of what is known as Hypercapnia. Which is when there are high levels of co2 and the fish has trouble ridding too much co2 from their blood and through their gills and so co2 levels in the fishes' blood rise and H2CO3 forms which causes the hemoglobin to not able to carry o2 and so the fish essentially suffocates to death regardless if the water is highly saturated with oxygen. Fish will gasp at the water surface because the co2 level is slightly less (so they can expel the co2 in their blood to breathe again/easier) than other areas of the tank because of atmospheric exchange/off-gassing.


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## Argus (May 22, 2013)

WaterLife said:


> @Argus
> From what I have read, co2 soluble levels and o2 soluble levels are independent of one another, meaning they won't displace each other, they will simply "expel/gas off" out of the water if in excess. The water will only hold a certain soluble limit/threshold of those gases.


I think there is some confusion about dissolved gasses in water reaching equilibrium with atmospheric gasses vs. water's saturation point for dissolved gasses. You can find lots of info online about equilibrium with atmospheric gasses, but little about how much dissolved gas water can hold. 

I found nothing to indicate water has separate mechanisms for holding O2 vs. CO2. If you have a source for this info, I would like to look at it.


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## Hoppy (Dec 24, 2005)

houseofcards said:


> That was always my view on pearling. The plant is producing O2 at too quick a pace to be dissolved, although I guess 'pearling' can occur if the water is saturated as well.
> 
> If you have pearling in a thinly-planted setup, then I would reason to believe it's that particular plant that is producing O2 very quickly.


Oxygen doesn't dissolve in water nearly as readily as CO2 does. Pearling means oxygen is produced by the plant faster that it can dissolve into the water, so it forms bubbles. It doesn't mean the water is saturated with Oxygen.


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## houseofcards (Mar 21, 2009)

Hoppy said:


> Oxygen doesn't dissolve in water nearly as readily as CO2 does. Pearling means oxygen is produced by the plant faster that it can dissolve into the water, so it forms bubbles. It doesn't mean the water is saturated with Oxygen.


So we agree, LOL


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## essabee (Oct 7, 2006)

In about the year 1962/3 in school our science teacher used a mirror to direct sunlight into the planted tank in the shady veranda (open porch) of the school bursary and collected the streaming bubbles with a inverted conical funnel into a water filled inverted test-tube; then demonstrated to us that the gas was oxygen by rekindling a glowing matchstick with it.

Submerged leaves/stems grown by aquatic plants do not have any stomata like openings or thick cuticles and gases diffuse across the leaf/stem surfaces. So when you see a steady stream of bubbles escaping from any point of a submersed plant - it certainly is not escaping from a stomatal opening. Submersed plants have developed a system of very large gaseous intercellular spaces - this helps them to have a positive buoyancy and also a storage for gas, usually oxygen. So when a leaf/stem of a aquatic plant is bruised; a stream of gas bubbles out at a rate proportional to the rate of photosynthetic activity of the plant.

You may be interested to know that there are aquatic insects that poke their air-tubes into the arenchyma of aquatic plants to replenish their oxygen without coming to the surface to breathe.

In an uninjured plant the excess oxygen escapes by diffusion through the surface of the leaf/stem into the water. If the plant is producing more oxygen than it can store and also lose by diffusion into the water - bubbles will form. The formation of bubble needs a nuclei - usually a colloidal spec of gas - on the surface of the leaf/stem of the plant. The bubble will grow if the state of production remains at that high level. This bubble will continue to adhere to this point and grow and may even coalesce with nearby bubbles. This continues till the force of its buoyancy makes it flow away wholly or in part. This is pearling and it does not only happen when the water is saturated with gas (oxygen or other gas mixture). If the water is saturated with gasses the rate of oxygen escaping a plant by the process of diffusion during photosynthetic activity is greatly reduced.

Pearling therefore occurs when the unstorable oxygen produced by the, photosynthetic activity of an aquatic un-injured plant cannot be lost by diffusion into the surrounding water.

When we use CO2 gas to induce higher rate of photosynthesis - we are dissolving CO2 into the tank water. Part of this CO2 reacts with water and part of it dissolves in water as gas. This makes the water more gas saturated than if we were using glutaraldehyde to induce higher rate of photosynthesis. This higher gas saturation while using CO2 makes it more likely to observe the phenomenon of pearling. Also again glutaraldehyde is usually used by those who have lower light levels in their tank - therefore lower rates of photosynthesis. Then that does not mean that pearling cannot occur when photosynthesis is increased by use of glutaraldehyde.


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## houseofcards (Mar 21, 2009)

essabee said:


> In an uninjured plant the excess oxygen escapes by diffusion through the surface of the leaf/stem into the water. If the plant is producing more oxygen than it can store and also lose by diffusion into the water.


Good stuff

Is it possible that a plant can be pushed by co2 and other factors to produce o2 at such a pace that the plant actually develops a 'fissure' of sorts and the o2 is expelled in that way. Technically an internal injury. 

When a stem is cut it's obvious that the larger o2 bubble is a result of that. But I've had plants that do stream and are uninjured. The stream is extremely small and expels almost mist size bubbles, but nevertheless there is a stream.


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## essabee (Oct 7, 2006)

houseofcards said:


> Good stuff
> 
> Is it possible that a plant can be pushed by co2 and other factors to produce o2 at such a pace that the plant actually develops a 'fissure' of sorts and the o2 is expelled in that way. Technically an internal injury.
> 
> When a stem is cut it's obvious that the larger o2 bubble is a result of that. But I've had plants that do stream and are uninjured. The stream is extremely small and expels almost mist size bubbles, but nevertheless there is a stream.


Laughing (photosynthesising) till you split. 

Good to imagine; but I don't think the evolution and natural selection would allow such aberrations to continue to exist.

In all probability the injury suffered is too tiny to meet the eye.


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## houseofcards (Mar 21, 2009)

essabee said:


> Laughing (photosynthesising) till you split.
> 
> Good to imagine; but I don't think the evolution and natural selection would allow such aberrations to continue to exist.
> 
> In all probability the injury suffered is too tiny to meet the eye.


LOL,

That's funny, but with pressurized co2 the plant could find itself in an optimum growing condition, but one that isn't really natural just one the aquarist prefers.

EDIT: If you look at this picture of the Java Fern pearling, you could see plenty of pearling, but there are several streams (arrows) coming from the plant as well, injury?, probably not. Yes this plant is very happy, literally splitting it's sides? LOL


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## essabee (Oct 7, 2006)

You propose a hypothetical situation of over-driven photosynthesis.

In natural course of a submersed leaf of an aquatic plant during photosynthesising period the oxygen produced is diffuses into the inter cellular spaces of the leaf as gas more than into the water body as the later process is slow. In natural course also the pressure of the gas stored in these inter-cellular space (lacunae) is higher than the external pressure on the leaf's surface. In fact this higher pressure is used by the plant to create the lacunae at the growing tips. It is also true that the cuticle, of the leaf (surface skin) is not thick and usually flexible to allow movement with water currents.

So putting the natural conditions into your hypothetical situation; there can be a rupture of the cuticle which allows a streaming of bubbles.

Then again in natural situations the aquatic plant also transports this oxygen by the leaf veins - petiole - stem to its root which need it as those usually are in anaerobic mud. So a split in the cuticle due to gas pressure would definitely be a disadvantage to the plant. More so a such splits would also bare the plants inner cells to pathological attacks. During the course of evolution such weaknesses would have been addressed for weeding out such weakness.

Then no one can actually argue in a hypothetical situation - so you could be right.


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## plantetra (May 17, 2014)

WaterLife said:


> ^
> 
> I thought pearling only occurred when the oxygen solubility limits of the water volume have been reached, and thus bubbles of o2 are formed, but do not dissolve because the threshold of o2 has already been reached.
> 
> Essentially there is more o2 (being produced) in the water than it can hold.


There are few scientists here. It took a turn but really good info. So I would still think that the light is the limiting factor for pearling. If the intensity is not high enough, pearling may never take place provided you have high CO2 and ferts. I have also noticed that I have extra pearling on the days I have a watrerchange even though my CO2 injection remains the same. Clearer water? Extra oxygen? What is it?


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## Argus (May 22, 2013)

plantetra said:


> So I would still think that the light is the limiting factor for pearling. If the intensity is not high enough, pearling may never take place provided you have high CO2 and ferts.


I would think any one of the holy trinity (light, CO2, nutrients) could be the limiting factor for pearling. You need active photosynthesis for pearling. Limit any one of those three and you limit photosynthesis.


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## WaterLife (Jul 1, 2015)

plantetra said:


> There are few scientists here. It took a turn but really good info. So I would still think that the light is the limiting factor for pearling. If the intensity is not high enough, pearling may never take place provided you have high CO2 and ferts. I have also noticed that I have extra pearling on the days I have a watrerchange even though my CO2 injection remains the same. Clearer water? Extra oxygen? What is it?




I don't know very much and was just trying to give a somewhat educated guess as to what was happening, but apparently I am wrong on this one, and I apologize for the misinformed answer, so I would listen to those with a better understanding of this.


As Hoppy mentioned in post #20 and what Essabee talked about just a few posts up.


As for the "false pearling" during water changes maybe that is sort of like the o2 pressurized injection so there really is more o2 than the water solubility can hold or just lots of bubbles from the water change and they are too slow to dissolve so they remain and/or just float up slowly out of the water. But I too get false pearling during water changes (even on low tech tanks!) and on some plants it does very well look like the plant is actually pearling (producing the o2 bubbles) and not just having bubbles slide against it as they float up. I've seen steady streams of micro bubbles come out from spathes and out from where the petiole meets the underside of leaf. So maybe water changes somehow give the plants a huge boost in photosynthesis/o2 production, because again, as stated, I've seen this happen in my low tech tanks (usually no huge bubbles under leaves, but I have seen lines of bubbles that really do looked produced by the plants in damaged areas and UNdamaged areas). Just my thoughts on that.


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## plantetra (May 17, 2014)

WaterLife said:


> I don't know very much and was just trying to give a somewhat educated guess as to what was happening, but apparently I am wrong on this one, and I apologize for the misinformed answer, so I would listen to those with a better understanding of this.
> 
> 
> As Hoppy mentioned in post #20 and what Essabee talked about just a few posts up.
> ...


We can rule out the bubbles trapped during water change because I do water in water out water change. So there is no disturbance to water level or no extra agitation during a water change. I still get a lot of pearling.


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