Pearling discussion

[Sb1415]

Did not want to hijack another user's journal, so thought i would start this to discuss pearling in plants. Overall there seems to be a general agreement that pearling would indicate good plant health in the presence of a co2 saturated water.

Although there is likely multiple variables and factors involved, I am curious to understand the pattern in other aquarists. Thought I would share what i see in my tank and see how it compares to others,

- For note in this I have stated pearling as to the presence of bubbles on the leaves

Tank Specs
Co2: 40 - 50 ppm
Fert dosing: Lean
Lights: 50 - 60% intensity (it would be ideal to have the PAR rating, but I don't personally have a meter)

Pearling
Indicator plant: Rotala blood red/Rotala tulunadensis
Start of pearling: 2 hrs after lights on
Peak pearling: 3-4 hrs after lights on
Pearling not present: 5 hrs after lights off

 

[ElleDee]

I have never injected CO2, but in my higher light tanks, if they are going very, very well, I sometimes will see pearling by the end of the lights on period. Pearling relates to oxygen saturation from photosynthesis rather than being directly connected to CO2. I've never really tracked it in detail, but Rotala 'Blood Red' was the easiest to get to pearl for me too.

 

[Sb1415]

I have never injected CO2, but in my higher light tanks, if they are going very, very well, I sometimes will see pearling by the end of the lights on period. Pearling relates to oxygen saturation from photosynthesis rather than being directly connected to CO2. I've never really tracked it in detail, but Rotala 'Blood Red' was the easiest to get to pearl for me too.

Interesting concept about it indicating o2 saturation and not co2 saturation. I had a wrong understanding that there is a fixed capacity in the water for any gas and if it gets saturated with co2, then o2 would not dissolve. I assumed this is why fish sometimes struggle in high co2 tanks due to the lack of o2.

But reading more about this, looks like each gas has its own solubility limit governed by Henry's law and the pearling should occur after the tank is saturated with oxygen. Given this the fish likely struggle from hypercapnia (more co2) rather than hypoxia (less o2). This also explains why the pearling is present after co2 is turned off and the the Co2 measures lower.

 

[snowballs99]

I can induce pearling with no CO2, just using an extremely intense light.

LIkewise you can also have pearling with high CO2 and low light.

It's an indication of photosynthesis speed if anything. Bubbles are forming too fast on the plant for the water around it to diffuse it.

 

[Tim Harrison]

It’s to do with the rate of photosynthesis and O2 saturation of the water column. The water column becomes saturated with O2 so no more will dissolve and therefore forms bubbles.

Plants can be perfectly happy without exhibiting pearling. High light induces it. But it’s something that requires balance. Highlight can quickly go south, like Venezuela.

Not in the narco-terrorist sense but in terms of algae outbreak…

 

[BenB]

In years past I've seen arguments over pearling. People saying even sick plants will pearl, so it means nothing.
It's true, but in my experience, the quality of the pearling is different from healthy plants as from struggling plants.
I've had tanks in the past that started pearling within minutes of the lights coming on.

For my present tank
CO2 50ppm+
Fert Dosing: EI
Light: 124 PAR

My plants start pearling fairly quickly in this tank. Usually about 30 minutes after the lights come on. I have a good number of plants right now, so the water reaches O2 saturation pretty quickly.

 

[ElleDee]

In years past I've seen arguments over pearling. People saying even sick plants will pearl, so it means nothing.
It's true, but in my experience, the quality of the pearling is different from healthy plants as from struggling plants.

...Do they? Or are people talking about the air bubbles that come from wounded plant material? I think those are formed from either the reactive oxygen species that are created as a response to damage or possible from the physical disruption to oxygen flow within the plant. In my mind that's superficially similar to pearling but not the same, though perhaps that's an issue of semantics more than anything. I have seen algae pearl though and that sure doesn't scream plant health.

If they mean pearling in the usual sense I'd need to see it to evaluate. I certainly have seen people claiming that plants that seem healthy by traditional are secretly not but I have never found it very convincing, so I'm curious if this argument is similar or if this is just something I'm unfamiliar with.

 

[Naturescapes_Rocco]

Adding my $0.02:

I've definitely seen and used pearling as indicators too often for it to be placebo/false in regards to plant health. Like Ben said, yes unhealthy plants pearl -- but healthy plants pearl differently.

With my setups (high light, CO2, ferts in WC) if my plants aren't pearling it's almost always a precursor to algae within the next few days or so. If I don't see pearling, it's usually been:

• Macros are running lower than they should
• Micros were overdosed or severely underdosed
• CO2 has run out or didn't come on at the time I set, or there's a leak, etc.

For these high energy setups pearling has been, for me, a definite indicator of plant health -- but the kind of pearling matters, quite a lot. It's hard to describe, but once you know, you know!

 

[BenB]

...Do they? Or are people talking about the air bubbles that come from wounded plant material?

Can they not do both? I don't think a plant that isn't happy is necessarily always also damaged. They might be, but they don't have to be.
Pearling from damaged plants tends to be a steady quick stream of bubbles. To me it is different from the pearling I'm talking about which seems random.

If they mean pearling in the usual sense I'd need to see it to evaluate. I certainly have seen people claiming that plants that seem healthy by traditional are secretly not but I have never found it very convincing, so I'm curious if this argument is similar or if this is just something I'm unfamiliar with.

I think you'd need to see pearling in a healthy CO2 injected tank and you'd know. It's just very different. Slow steady release of bubbles. It's like the plants are breathing rather than gasping.