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Plants pearling


27 Dec 2009
Denton, Manchester
I think thats a really interesting article. I agree that having much stronger lighting can help Pearling happen if co2 is in enough concentration but also on the other end ive had Pearling in lower lighting but in which the tank had a much softer flower.
I also noticed pearling when filters are turned off or flow is really reduced.

Hell I even get pearling in my low tech on water change day which shows that high light is not needed to see this.

However I, and im sure a few others may agree, believe that you dont have to have pearling to mean your tank is tip top. I know it doesn't state that pearling is essential but alot of people chase the 'pearling dream' in thinking that it must mean everything is how it should be and if no pearling then the tank isnt right.

Not sure why it mentions the need for blue/green algae to have pearling though. Unless it meant to see it happen have a tank with it in for test purposes

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18 Apr 2013
I get periodical pearling for no apparent reason with no change in routine or dosing. The plants just decide to pearl now and again. Not sure if it could be the amount of sunlight hitting the tank in a particular day as it's really the only variable. Nice to watch when it does pearl - wish it would do it more often :D


7 Apr 2008
nr Bath


Expert/Global Moderator
11 Jul 2007
Chicago, USA
I see that many folks still have questions about pearling, especially why it isn't happening in their tanks. :)

So here's a nice article I've found, feel free to discuss it further:

Pearling - True or False?
Mike there are several flaws in that article. It is unnecessary to supersaturate the water with Oxygen in order to see pearling. Therefore, his claim that a single plant will not pearl just because it is sitting in a large volume of water is not valid. Pearling is a phenomenon which is based on the RATE of Oxygen evolution. Oxygen does not have a very good solubility in water, so if the evolution rate exceeds the dissolution rate the gas will form bubbles.

The rate at which Oxygen is produced is directly proportional to the rate of photosynthesis. In turn, the photosynthetic rate depends on many factors such as light intensity, CO2 availability, nutrient availability, temperature and overall plant health. Likewise, the solubility of Oxygen will depend on pressure and temperature.

So all these variables will combine to determine how quickly Oxygen is released into the water and whether the gas will dissolve immediately or not.

Also, the strategy of Oxygen release is not necessarily due to the toxicity of Oxygen. The evolution of Oxygen is really a side issue that occurs when the O.E.C (Oxygen Evolving Complex) in the chloroplast disassembles the water molecules into it's constituents Hydrogen protons (H+) and Oxygen. The O.E.C wants the H+ because these protons are used in the almost the same way as a battery. It stores the H+ protons and this potential to generate energy in the form of a phosphate enzyme called ATP (Adinosine TriPhosphate) ATP is a recyclable enzyme which all living things use to generate energy.

Surplus Oxygen produced by the chloroplasts O.E.C is sent to the roots to oxygenate both the roots themselves as well as the sediment. This is a symbiotic relationship between plants and microorganisms in the sediment. Nitrifying bacteria are aerobic and therefore, it is in the plants interest to supply Oxygen to these microbes to ensure their survival. There are other aerobic microbes that convert certain compounds to chemical forms that can then be used more effectively by the plant. The mere fact that microbes will use the Oxygen and will burn their food means that they will then release CO2 as a byproduct of their metabolism. This is CO2 that rooted plants can use.

You will find that those plants that are so called "Heavy Root Feeders" do not really care any more about sediment nutrients than plants that are not Heavy Root Feeders. One of the most important reasons for having a large root architecture such as Swords and Crypts is because the more roots that are in the sediment, the higher the distribution of Oxygen into the sediment and the higher the potential of sequestering CO2 from the sediment from a larger microorganism culture than plants with only a very puny root system.


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