pearling conditions

SuRje1976

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Feb 19, 2006
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I just skimmed through this thread and apologize if this had already been mentioned. :eek: Since pearling could also be an indication of O2 saturation, perhaps the non-pearling aquarium is low on oxygen? I had a similar experience where all of my other parameters were in line, but the plants did not pearl much. It was like this for several weeks before I suspected an O2 issue. My remedy was to raise one of my Lily Pipes slightly above the surface to agitate (and in turn, oxygenate) the water. One could predict that this would lower the CO2 levels in the water as well. I did not alter my CO2 bubble rate intentionally for this "experiment." With the pipe raised I got pearling in a day or two that was out of control.

I was able to repeat the "experiment" by lowering the outflow to its original position. Pearling decreased dramatically. So now I keep one of the outflows just slightly above the water surface all the time. Plants pearl nicely. ;)
 

ccLansman

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Jan 22, 2008
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interesting since pearling is due to plants getting rid of oxygen correct? Dont they use the co2 + phtosynthesis to product o2 on the other end?
 

SuRje1976

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Feb 19, 2006
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ccLansman;27674 said:
interesting since pearling is due to plants getting rid of oxygen correct? Dont they use the co2 + phtosynthesis to product o2 on the other end?


Exactly! Tom would be better at explaining the physiology and pathways involved for sure, but the plants utilize the carbon from the CO2 through photosynthesis, and produce O2 as a byproduct. The O2 that is produced is in solution, but when the aquarium water is supersaturated with O2, it comes out of solution into gaseous O2, also known as pearling. So if the aquarium water is low on oxygen, the plants may very well still be converting CO2 into O2, but the O2 is able to stay in solution because the aquarium water is not supersaturated, and able to accept the dissolved oxygen. Hence no pearling.
 

SuRje1976

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Feb 19, 2006
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ccLansman;27677 said:
o boy :) so now do we need high co2 levels or high o2 levles :)

Both would keep everyone happy! Plants, fish, and aquarium observers of the human variety! ;)
 

JJP2

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If you want to see your plants pearl, they will need to photosynthesize at a high rate which means plenty of light, nutrients, CO2. The tank water will need to have a very high O2 concentration so that it will become saturated and the O2 given off will not disolve in the water but form bubbles which will raise to the top of the tank.
 

Carissa

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Jun 8, 2007
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This would make sense to me, since yesterday when I did a water change (water probably being full of o2) I saw pearling all day. Today, I see no pearling. Nothing has changed other than the fact that I didn't do a water change today.
 

ccLansman

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Jan 22, 2008
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interesting thread thus far! I have to agree that after a water change the plants pearl like crazy, i though it was o2 bubbles sticking there from me mixing up the water with new water. But if in fact pearling happens as a result of o2 not dissolving, should we then want a healthy amount of surface agitation to encourage pearling all the time?
 

Mooner

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Yes surface movement is good as long as the surface isn't broken. CO2 will come out of solution faster that O2 can be dissolved into solution through surface agitation. I use a lot of surface movement and a overflow. This does use a bit more CO2 but I've been able to overall add more CO2 than without surface movement. Also using an internal powerhead for flow/mixing which between the two has allowed higher CO2 rates with no gasping of fish.
 

ccLansman

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Jan 22, 2008
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gotcha but was not really going for more co2 necessarily just more pearling due to high o2 concentration with sufficient co2 concentration.
 

VaughnH

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An unanswered question is whether the water in the aquarium has to be saturated with oxygen for pearling to occur. As I recall Tom told us months ago that it doesn't. It is only at the leaf surface that the water has to be saturated, as I recall.
 

Carissa

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If that is the case, then less circulation should lead to more pearling. Good circulation would move the o2 saturated water away from the leaf surface quickly. But then, co2/nutrients would be hampered from getting to the plant too. Anyone want to invent a drop checker for o2? That could come in handy. What are the properties of o2 saturated water vs. non-saturated water? There must be a way to test it.
 

ccLansman

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Jan 22, 2008
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ide have to agree with carissa, seems like at the LFS their cube has 0 water movment and everything is pearling like mad, so what do we do to get nutrients to the plants yet allow pearling to take place?
 

detlef

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Pearling can and does appear before 02 saturation levels have been reached. Also high current blows 02 bubbles quickly away from the plant so that the aquarist has a bad chance to see it. That at least has been answered by Tom as I recall. The real issue to me is: Why does improved pearling occur with additional 02 injection?

Clearly we have to separate better pearling after water changes from more pearling with injected 02 via airstones, lily pipes etc. The first might be easily explained by the fact that tap quite often contains lots of CO2 which can spurt photosynthesis. Also tap sometimes holds lots of 02 which then sticks to plants as tiny bubbles after wc's. Whereas the reasoning for better pearling with additional 02 injection has not been discussed so far to the best of my knowledge.

Logic tells me that it cannot be the 02 in itself since plants produce it as a by-product from their own activity (photosynthesis). Two ideas came to mind. Either there is something in the added 02 which plants can feed on (N2 gas etc.) or the water's pressure is raised immediately when 02 injection starts which in turn urges 02 to leave the plant easier and faster. The phenomenon can be observed and repeated ad infinitum. Hopefully someone more knowledgeable can shed some light on this.

Best regards,
Detlef
 

VaughnH

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If the tap water we add at water changes is saturated or even super saturated with oxygen, for at least a short time all of the plants would have saturated water at their leaves. Then, if they are growing at all, they should be pearling.

I'm not sure why we want to see pearling, except as verification that the plants are growing well. It isn't that attractive, and it can even be distracting, like fine particles floating around in the water. I enjoy seeing it occasionally, just to convince me I'm doing something right, but I wouldn't do anything to increase it.
 

Gerryd

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Vaughn,

I'm not sure why we want to see pearling, except as verification that the plants are growing well. It isn't that attractive, and it can even be distracting, like fine particles floating around in the water. I enjoy seeing it occasionally, just to convince me I'm doing something right, but I wouldn't do anything to increase it.


Most of the threads I read seem to have an opposite view :D

At least for me, I do find the pearling attractive, especially in the Riccia.........
 

VaughnH

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Pearling is certainly interesting to see. I don't have Riccia or any other plant that looks much different when pearling, so that might color my opinion. Since I am in the process of rebuilding my aquascape totally, using only low light plants, I haven't been fertilizing or trying to maintain any level of CO2. And, I have my light raised up 6 inches to reduce the intensity to the equivalent of about 1.5 watts per gallon. Today I noticed I have lots of pearling of the remaining plants in the tank. Weird!