# Bubbles appear in a tank at the end of a day



## igor.kanshyn (Jan 14, 2010)

I have lost of bubbles that appear in a tank at the end of a day. They are sitting on tank sides and on the plants.
That aquarium is covered with algae and some of that algae is a already dead.

There is no ammonia and about 5ppm of nitrates.
These bubbles appears at the end of a 'light-on' day and they disappear during night.

What can cause them? Are they are harmful?


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## bae (May 11, 2007)

Could be 'pearling' -- the plants producing more oxygen than the water can absorb.

If the temperature fluctuates a lot, e.g. the lights heat the water so that the temperature is much higher at 'lights off' than at 'lights on', it could be dissolved air coming out of solution as the water warms.


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## KhuliLoachFan (Mar 8, 2008)

Pearling is not only harmless, it's a sign your plants are doing well.

W


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## waj8 (Jun 30, 2010)

Algae will pearl. I find that under high light conditions the pearling starts almost right away. Under lower light it tends to start at the end of the day. Pearling doesn't occur until the oxygen level in the tank has reached the saturation point. So I would say your tank doesn't reach oxygen saturation until the end of the day. The bubbles on the glass are probably from the algae. Maybe not though.


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## george (Apr 11, 2009)

I get the same thing on my shrimp tank with moss and algae on the sides when i exceed the 8hrs lighting period. Could be pearling from the algae... or the tank is having fun ...


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## igor.kanshyn (Jan 14, 2010)

Pearling from algae doesn't look real for me. Pearling can happen for fast-growing plants, algae is not that one.
My algae is half-dead. And I'm thinking that it's roting and release _hydrogen sulfide_ or other bad stuff.
I can't read any ammonia in that tank and nitrates as very low as well ... it should be something else ...


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## waj8 (Jun 30, 2010)

If it were H2S any fauna would be dead by now. It is really pretty poisonous and very smelly. H2S is produced by anaerobic bacteria. The bubbles are clearly related to the lighting. If it's not oxygen then could it be that uses light to produce a gas? What killed the algae?


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## qwerty (Dec 15, 2009)

Well, my crypts pearl and they don't grow particularly fast at all... I wouldn't say it's only the fast growing plants that do it.

You keep shrimp, right?

I'm sure if there was something wrong you'd notice the shrimp starting to react by now.

Otherwise... I noticed when I was using a bubble ladder for CO2 injection that the bubbles would collect at the surface of the water. The same happens with my reactor when it gets the odd 'burp'. Perhaps if you're using an atomizer or something it's just undissolved CO2 bubbles sticking to your plants?

I've also noticed after a water change oxygen bubbles tend to gather up on my plants.


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## igor.kanshyn (Jan 14, 2010)

Thank you for the answers guys.

For now I see that it *was oxygen*.

Because my pH are changing during the day significantly.
The only explanation I see that during the day my plants and algae use CO2 from water column.
It makes pH higher. The visible bubbles are released O2.


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