# Plants not pearling



## rjordan393 (Nov 23, 2012)

Looking for possible cause?
pH range is 6.57 to 6.70 using pressurized CO2 and pH controller.
Kh before water change is 3.36 degrees. After water change, 4.48 degrees.
Gh before water change is 7.84 degrees. After water change, 8.96 degrees.

Tank is a 75 gallon. Filtration is by two 350 magnums. Their spray bars are submerged to provide more current. There is very little surface movement.
My CO2 checker does not indicate too much CO2. It is clear green.
About 4 weeks ago, I started to add buffer to try and maintain close to 4 dKh and I think this may be related.
I also use Seachems Equalibrium.


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## Yo-han (Oct 15, 2010)

Set your pH controller to 6.0 or even lower. (Mine is 6.1 with KH=5.7 before they start pearling a little on top of the rotala) the bottom needs even more light/co2. A friend of me tested it yesterday with low light and deadly amounts of co2. Glosso pearled like crazy.


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## rjordan393 (Nov 23, 2012)

Thanks,
But I wonder why they pearled when I first set up my pressurized CO2 system and for the last few weeks suddenly started to pearl less until none is visable. I can try adjusting my controller but first I want to check the calibration on it. It's been only 6 weeks since it was calibrated and I do not think it out of adjustment that soon.
One other thing; I heard on the net that nitrification stops at a pH of 6.00 and it has me concerned. I guess it would have to be much lower then that as yours is doing well.


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## Yo-han (Oct 15, 2010)

It won't stop at an certain pH. Bacteria work better at a higher pH. When dropping the pH below 6.5 they work less efficient and the lower you get the worse it gets. That is why I aerate at night. More oxygen, less CO2, higher pH and the bacteria can do their thing. During the day, they can take a break, haha.
If you don't like the low pH, increase KH, this way you can get much CO2 in the water with a higher pH. 

The first you set up CO2, they loved the CO2 even although it wasn't that much. Think of getting a nice burger for the first time. But after getting one every day, you pearl less too
Another reason might be that your aquarium is getting dirtier. If the water contains lots of organics that require oxygen, your plants need to produce more oxygen before they start to pearl.

PS. Remember, not all livestock can take a sudden increase in CO2 well. Always check your fauna every hour after increasing CO2 and aerate if they can't take it. Do it slowly! Plants don't need to pearl to grow healthy!


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## rjordan393 (Nov 23, 2012)

I read up on oxygen and plants and I did not know that they consume oxygen at the same time they produce it. The difference is they produce more then they consume. So last night, I came to a conclusion that if artificial means are used to provide more CO2 then its appears that one should consider aerating the tank at night. So I went ahead and hooked up an aerator today to turn on at night and will adjust my controller down to 6.60 for a center point or until my CO2 checker tells me I have sufficient CO2; afterwhich it should shut down.
I believe my system was starved for oxygen at night and was not prepared for the next day to photosynthesize.
I will take it slow and make a decision on whether to raise Kh or keep it as is.


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## modster (Jun 16, 2007)

I could be wrong, but from my personal observation, pearling can stop after a water condition change. I would leave everything as is and see if the pearling will start again in a few days.


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## rjordan393 (Nov 23, 2012)

Ok,
The pearling has started but not as much as before. Here is what I believe was happening and is only a theory. About 3 or 4 weeks ago, I removed a small powerhead that was used for aerating at night. It seems that if more CO2 is added then what is available in the air, then it seems that the plants will need more oxygen by an aerating device to help balance things out overnight. I believe if we do not do this, then the plants will not have enough oxygen in them to perform photosynthesis sufficiently the following day. Also Kh seems to play a role here. 4.48 dKh or 80 ppm appears to be the low end to be; at least in my case. Today, I also adjusted my pH controller shutoff point to 6.47
and added a 0.50 tsp buffer to help bring up my KH to near 5.00 dKh. So far, the fish are doing fine.
However, there is a disclaimer to the above. Those who have heavily planted tanks may not even need an aerator for overnight use. Only your experience will determine that.


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## Yo-han (Oct 15, 2010)

I don't think this is what happens. My theory: Pearling happens when the O2 saturation is more than 100%. When O2 drops low at night, your plants need to produce a lot of O2 before it goes over 100%. When you aerate at night, you maintain high O2. Now plants start pearling sooner because they oversaturate the water sooner. Sounds plausible right...


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## rjordan393 (Nov 23, 2012)

I think we are close to the same page. The over saturation must occur during the light out period because once photosynthesis starts, it relies on the oxygen that was stored the night before. This gives a head start on the process. Less we forget, as soon as the CO2 is injected means oxygen is being removed or overcomed by the higher amount of CO2. But is it enough? Otherwise we may not need to aerate our tanks at night. Don,t forget, my theory is based on lightly planted tanks.


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## houseofcards (Feb 16, 2005)

I always thought 'true pearling' was based on how fast the plant was producing O2. The pearl is seen since it can't dissolve into the water fast enough. I'm pretty sure I've had pearling in very thinly planted iwagumi-style tank.


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## Skizhx (Oct 12, 2010)

I get pearling in my small soil-based setups that don't receive any CO2 injection. I also don't have any water movement in these setups so there is minimal off-gasing of CO2 overnight, but at the same time, there's minimal aeration.

However, I've seen pearling in both the setups that received low-lighting, and the setups that were lit by morning/noon sun.

So by this reasoning, people who are running CO2 injection should see pearling almost regardless of their lighting... But apparently that isn't the case... But at the same time people with high lighting and CO2 injection don't necessarily see pearling either...

To me this says there's a piece of the puzzle that's being overlooked here...


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## rjordan393 (Nov 23, 2012)

I have a hunch it all related to how much CO2 is injected based on the Kh. I seen a message from someone stating that the pH/Kh/CO2 chart is not always right because other forms of hardness can interfere with the test reading. If that's the case, I and others may be underdosing CO2. I think Tom Barr is a botanist and will contact him to see what advice he has.


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