# High Surface Tension; CO2 bubbles won't pop



## tjc (Jan 17, 2006)

I just started my DIY CO2 last night and by this evening the surface of the water is covered in bubbles circling the aquarium. I forgot to use Novaqua when I did my 50% water change last night. Is this something I should be concerned about, the bubbles not popping?

pH=7 (down from 7.5); dKH=8; CO2=24ppm

I'm using a Coralife wooden airstone that is making the tinyist bubbles like that found in a protein skimmer. The bubbles take 3-5 seconds to float to the top. When I aim my power head on the bubbles floating up, they take 10 to 20 seconds to reach the top, but then they can just sit there for minutes when they get there. The power dispurses the bubbles so that it creates a mass of bubbles filling 2/3's of the tank volume.

I'm surprised that I could get CO2 so high with a DIY set-up in a 65G aquarium.


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## BryceM (Nov 6, 2005)

Are you sure the bubbles aren't coming from pearling too? If you have a surface film small bubbles will tend to collect. It doesn't hurt anything. If it bothers you do a search for mollies or protein skimmers (sounds like you know more about them than me) - both can help.


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## tjc (Jan 17, 2006)

Yeah, I have a film covering the surface. It's partly due to dust though most of the aquarium is covered well. Dust is a problem in the winter months here in Central New York with the heat running through the vents so often.


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## wiste (Feb 10, 2006)

Maybe I am confused about semantics. A protein skimmer is used in a saltwater aquarium. Some protein skimmers use wooden airstones to create fine air bubbles. If I understand, the wooden airstone is being used to add CO2 to the tank.

A surface skimmer attached to a filter intake would reduce surface tension. I do not think there are protein skimmers for freshwater. If so, please clarify.


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## niko (Jan 28, 2004)

You are experiencing a common thing - lack of enough surface agitation. That will lead to a huge increase of CO2 in the water but unfortunatelly you will also notice that the plants don't really grow well.

From my experience increasing the surface agitation in such a tank leads to great plant growth. I believe that the reason is that proper gas exchange takes place, some oxygen loving bacteria start to function normally, and a balance is established.

Just raise the output of your filter closer to the surface so it makes some ripples and you should be ok.

Also - if you have DIY CO2 and a powerhead in the tank already try a little trickery; Put the wooden airstone under the powerhead so it sucks all or most of the bubbles coming from the stone. You will see that they get chopped up and expelled by the powerhead as much smaller bubbles, almost as a mist. In addition they are distributed much further thanks to the powerhead flow. All that will help maintain the CO2 in the tank at a high level while the surface agitation is increased.

--Nikolay


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## tjc (Jan 17, 2006)

I think that the wooden airstone may be too much as it produces bubbles so fine they are easily swayed by the water movement and I end up with a blizzard of bubbles. The larger bubbles definately reach the surface and pop faster.

I definately have a problem with surface scum and outside of surface skimming, my only option is to use a brine shrimp net to try to clean it up every now and then. I do have a skimmer cup that I've used when doing water changes and I didn't use it with the last water change. Maybe I'll rig it up to my Hagen Aquaclear 70 HOB filter for a half an hour.


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