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Why do I bother?

Maybe because you haven’t given up on us, yet .

So basically you say the same than I did in the conclusion of my last entry. To sum it up:

- Pearling is a sign of O2 saturation. This is not necessarily a sign of strong plant growth.
- Comparing pearling between our tanks does not indicate that one person’s “treatment”, like ferts and CO2 additions, is more successful than another person’s. Too many other factors, like fish load and default O2 saturation levels, are participants in the pearling process.

Well, I guess that answers the original question. I guess such questions pop up in my mind when I wonder the streets of Manhattan on my way to work and the brain freezes over. Let’s see what other crazy thing I can come up with next .

Ingo

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Proud Member of the New Jersey Aquatic Gardeners Club

Either I never really listened when someone explained this to me

Why do I bother ?...........:%)

As usual it's a bit simpler then you all make it out to be

What is pearling ? Why do we see it when we see it ?

Plants when photosynthesing produce O2, correct? The 02 is dissolved in the water. Water can only hold a limited amount of O2. Once the water is saturated with oxygen , the O2 produced by the plants cannot dissolve so it becomes visible as small bubbles on the plant.

That's it really, there's no direct link between levels of Co2. You can have high Co2 and no pearling.

Of course to get to the rate of photosynthesis needed for the plants to produce such large quantities of oxygen you need good Co2,nutrients and light.

Pearling will normally be seen in the evening as it takes a few hours of photosynthesis for the plants to produce sufficient O2 to saturate the water and therefor start "pearling".

Now when you do a water change the tap water has a lot of Oxygen inside (it's been trapped in pipes, nowhere to outgas the O2). As a result when you do a water change you've got a higher saturation of o2 then normal, therefore the water supersaturates much more quickly when the lights come on and the plants get going.

Result = pearling starts quicker/earlier and is more intense.

Sometimes the bubbles of O2 get trapped under plant leaves and people mistake this for pearling. But generally you see faster stronger more intense pearling on water change day.

Pearling can be mis-leading. It's really more of an indication of o2 levels in a tank then anything else. Yes it can be an indicator that plants are doing well, but it doesn't mean a tank where there is less or no pearling is not doing well, it just as a higher capacity to hold O2.
A higher fishload tank will pearl less (more fish = more o2 consumed = longer time needed to super saturate water).
Warmer water holds less O2 etc.

LF you're tank pearls very heavily, large plant mass light fish population , so you're tank produces a lot more O2 then the fish need or the water can hold. Nice heavy pearling.

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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.

robbanp – Let me see if I understood your comments correctly:

You say that during the water change I basically saturate the tank water with 100% of O2. As such, even the smallest additional production of O2 by the plants would conclude in bubbles that otherwise would be consumed into the water to increase the saturation. Right?

That would make sense, but I can’t see why there would be an increase in plant growth during that time. I somehow would be willing to buy that a large surface agitation would “draw” more CO2 from the air into the water, but this is not the case. Although not having measured it, my ph would have to shoot down to hold all this CO2. In addition, I fill the tank by hanging the Python end into the water so any air contact is limited to the content of the vacuum part of the Python and surface agitation stays low.

NowherMan6 – For the same reason as mentioned above, there cannot be a super-saturation with CO2 – the ph is not falling like mad. A super-saturation with O2, yes, that is what I have in mind.

If this is true then any statement like “my plants are pearling like mad after a water change” has basically only a value of esthetics and tells us that the O2 saturation of the water has been reached.

Ingo

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Proud Member of the New Jersey Aquatic Gardeners Club

Hey LF

I remember bensaf talking about this somewhere in the dense pages of the multiple logs going on...

If I remember correctly - or close to correctly - a lot of the bubbling you see on the harscape, glass even on the plants is, as you've said O2. The bubbles fly around and get attached to everything. And it's this same super-saturation of 02 that makes the plants pearl witht he CO2 that's already been injected in the tank. Something along the lines of, it's when the water is supersaturated with both O2 and CO2 that plants do the most pearling.

Now chemisty people, go ahead and shoot me down!

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Back in the saddle!

First of all, the bubbles you see when the plants pearl are O2 and not CO2 but I suppose that was what you meant.


Let´s think about it and see if we can come to a conclusion;
Oxygen enters the water through surface agitation, the same way carbon dioxide escapes.
Do you ever get any more surface agitation then when you do a water change?
When you pour the water in (at least that´s how I do it), the water pulls a lot of little air bubbles down into the water column. These bubbles will contain both oxygen and carbon dioxide (think of this as the bubbles from your pressurized CO2 bottle, only mixed up with the other ingredients of air). Since you have already (probably) over saturated the water with oxygen (it can only hold so much) some O2 will already be forming and go of as tiny bubbles. At the same time the water will have taken up CO2 from the bubbles you "poured" in with the replacement water. This CO2 will probably be enough to make the plants have a short period of extra growth. Even if the plants do not produce more O2 than usual, what they do produce will pearl since the water is already saturated and can´t "take up" (I don´t know the correct expression here, if anyone understands what I´m talking about please do enlighten me) any more oxygen.

Does this make any sense or do anyone have a better explanation?

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So here I am once more...