# Co2 bubbles collecting on surface??



## Jeff5614 (Dec 29, 2005)

Are you noticing an oily film on the surface? The surface scum that plagues a lot of people can cause this. Increasing your surface agitation should take care of it.


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## So_Fishy (Jan 16, 2012)

Yes I notice a film too at times. Some days its worse than others and some days it isn't there at all. Would adding an airstone at night help too?


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## AirstoND (Jun 17, 2011)

Isn't white foam usually a sign of oil mixing with water? I figure oil is from cylinder tank/valve when using bottled CO2 or yeast mixture seeping into tank.

I use DIY yeast CO2 and never had this happen. I also use 3 bottles (yeast/sugar mixture, bubble counter, and third is filled with black carbon)


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## Jeff5614 (Dec 29, 2005)

So_Fishy said:


> Yes I notice a film too at times. Some days its worse than others and some days it isn't there at all. Would adding an airstone at night help too?


The film is why the CO2 bubbles are collecting on the top. If you can actually believe what ADA says ( yes, I'm being sarcastic, I believe them ), that surface film is an indication that your biofilter isn't functioning well. The increased aeration will help break up the film and it will also help your biofilter with more O2, not mention your fish. You can put it on a timer and have it run from lights off until lights on. Increased aeration can only benefit your tank.


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## tom g (Jan 2, 2010)

*surface bubbles*

*my tank is doing similar , i thought the idea was to not have surface aggitation ,i have pressureized c02 , what is a bio filter i am running a ehiem 2215 and a fluval 205 *
*thanks *
*tom*


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## AndreyT (Apr 28, 2011)

Well, surface agitation is a rather strange thing to suggest. You are injecting CO2. When you are injecting CO2 you generally want as little surface agitation as possible, since excessive surface agitation will drastically increase the amount of CO2 that escapes from the water to the air.

The right answer to the question of why they are collecting there is: your CO2 diffuser is producing bubbles that are too large. For this reason, your bubbles shoot up to the top quickly, without having enough time to dissolve. Either get a finer diffuser, or switch to an alternative injection method (reactor, canister filter etc).

The surface film is a secondary issue. If your water quality checks out OK and the fish is doing fine, then you can just ignore the film issue. You can also try removing that film from time to time by placing a sheet of paper on the water surface and quickly picking it up.


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## tom g (Jan 2, 2010)

*co2*

Thanks that's what I thought was the problem I believe
My reactor is not working properly as it stops spinning at 
times . Not sure what other way to go should I try another 
Reactor or should I switch to a diffuser any rec would
Be appreciated is there any reactors out there I should be 
Looking at 
Cheers 
Tom


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## Jeff5614 (Dec 29, 2005)

AndreyT said:


> Well, surface agitation is a rather strange thing to suggest. You are injecting CO2. When you are injecting CO2 you generally want as little surface agitation as possible, since excessive surface agitation will drastically increase the amount of CO2 that escapes from the water to the air.
> 
> The right answer to the question of why they are collecting there is: your CO2 diffuser is producing bubbles that are too large. For this reason, your bubbles shoot up to the top quickly, without having enough time to dissolve. Either get a finer diffuser, or switch to an alternative injection method (reactor, canister filter etc).
> 
> The surface film is a secondary issue. If your water quality checks out OK and the fish is doing fine, then you can just ignore the film issue. You can also try removing that film from time to time by placing a sheet of paper on the water surface and quickly picking it up.


I'm sorry but I'm going to disagree with most everything you've said. Surface agitation increases the amount of O2 in your tank which is needed by everything from the fish to the bacteria. The better your O2 levels the healthier the tank overall. Surface agitation will drive off some CO2 but it can easily be compensated for by increasing your rate of injection. Since CO2 and O2 exist independently, you can have high levels of each. Combined with good surface movement you also need good flow throughout the tank not only to move C02 and nutrients to the plants, but to move water from lower depths to the surface where gas exchange occurs and O2 can be absorbed. Allowing the film to remain just decreases the amount of gas exchange at the surface further lowering O2 levels even more. The main thing lack of surface agitation does is make it easier to gas your fish. Higher O2 levels also allow your fish to tolerate higher CO2 levels.

Bubble size has nothing to do with CO2 bubbles collecting at the surface. It's because of the surface film on the water which is due to an inadequate biofilter. A healthy biofilter in combination with adequate turnover in the tank, including surface movement will eliminate the film. A robust biofilter makes for a healthier tank by breaking down fish and plant waste that otherwise will remain in the water.

One thing you can do to help with surface movement is to install a skimmer. It will remove the film and carry it to the filter and once again increase oxygenation.

Oxygenation is as important in a planted tank as a fish only tank. Plants do aid in oxygenation but they're not the whole picture.


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## AndreyT (Apr 28, 2011)

Jeff5614 said:


> Surface agitation increases the amount of O2 in your tank which is needed by everything from the fish to the bacteria....Higher O2 levels also allow your fish to tolerate higher CO2 levels.


It is a well-known dilemma that CO2-injecting fishkeepers have to face. On the one hand, surface agitation is needed to supply O2 to the tank inhabitants. On the other hand, surface agitation wastes CO2. So, as usual in such cases, it is about finding proper balance between O2 supply and CO2 loss that works best for each specific setup. Obviously, "vertical" tanks with small surface area will need more agitation than "flatter" tanks with large surface area, for one example. 

Fortunately, it is not a problem at all, since practice shows that for a traditionally-proportioned tank even the minimal amount of surface agitation provided by a well-designed laminar outflow of a canister filter (i.e. just gentle mixing and no significant surface disturbance) is more than sufficient to fully supply the tank with oxygen. Which is why people who inject CO2 normally prefer not to increase their surface agitation. This is the basis of my advice above.

Of course, if you notice that the fish suffer from lack of oxygen, steps need to be taken to correct the problem. Most of the time it can be solved by realigning the filter outflow nozzle. There's no need for such drastic measures as "adding an airstone". An airstone in a CO2 injected tank is... well... it just makes no sense whatsoever.



Jeff5614 said:


> Bubble size has nothing to do with CO2 bubbles collecting at the surface.


Well, it now looks like an exercise in semantics to me. Obviously, if bubbles had a chance to dissolve before coming to the surface, they wouldn't collect there, would they? The number and the size of bubbles I see in the OP's picture suggests that too much CO2 is allowed to escape in this setup (film or not).



Jeff5614 said:


> It's because of the surface film on the water which is due to an inadequate biofilter. A healthy biofilter in combination with adequate turnover in the tank, including surface movement will eliminate the film. A robust biofilter makes for a healthier tank by breaking down fish and plant waste that otherwise will remain in the water.


Nobody is arguing with that the film might indicate a filter problem. However, it could be a temporary issue with filter that is not working at its full potential yet. (The tank appears to be recently set up. Is it?). I would perform occasional manual removal of the film and see if the problem eventually corrects itself, once the filter gets up to its full potential.



Jeff5614 said:


> One thing you can do to help with surface movement is to install a skimmer. It will remove the film and carry it to the filter and once again increase oxygenation.


There's no such target as "increase oxygenation" for no specific purpose in a CO2 injected tank (or any tank, actually). You seem to present "increase oxygenation" as some sort of ultimate goal that trumps everything else. In reality, as long as the current oxygenation level is sufficient for well-being of tank inhabitants, by attempts to increase through surface agitation make no sense whatsoever. It has no appreciable positive effects, and it has negative effects on the efficiency of CO2 fertilization.



Jeff5614 said:


> Oxygenation is as important in a planted tank as a fish only tank. Plants do aid in oxygenation but they're not the whole picture.


Nobody argues with the fact that oxygenation is important. It is not clear to me though what is the point of even mentioning it in the context of this discussion. The OP never stated that there is lack of O2 in the tank.


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## shane3fan (Nov 2, 2009)

the simple answer for the bubbles on the surface is surface tension. Now, you folks can argue over what is causing the water surface to be unbroken by the CO2 bubbles all you want--I will say that it isnt something I would worry about. The bubbles will either burst or dissolve into the water. Worst thing that could happen is insufficient saturation of the water column with CO2---but it looks like the OP has plenty of CO2 by the picture. 

The foam--thats a different thing--and I know lots of people have dealt with the surface film in the past, and Im sure lots more in the future. Ive heard people blame organics, overfeeding, etc for it---not sure if anyone knows exactly what causes it. From what Ive seen, it will eventually go away. 

To me, the most telling statement out of this discussion was made by the OP "None of my fish are showing any signs of stress. My plants are growing well."


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## Jeff5614 (Dec 29, 2005)

AndreyT said:


> It is a well-known dilemma that CO2-injecting fishkeepers have to face. On the one hand, surface agitation is needed to supply O2 to the tank inhabitants. On the other hand, surface agitation wastes CO2. So, as usual in such cases, it is about finding proper balance between O2 supply and CO2 loss that works best for each specific setup. Obviously, "vertical" tanks with small surface area will need more agitation than "flatter" tanks with large surface area, for one example.
> 
> Fortunately, it is not a problem at all, since practice shows that for a traditionally-proportioned tank even the minimal amount of surface agitation provided by a well-designed laminar outflow of a canister filter (i.e. just gentle mixing and no significant surface disturbance) is more than sufficient to fully supply the tank with oxygen. Which is why people who inject CO2 normally prefer not to increase their surface agitation. This is the basis of my advice above.
> 
> ...



I think we're just going to have to agree to disagree on a few of the points, which at least keeps things from getting boring  .


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## HD Blazingwolf (May 12, 2011)

oxygen is produced by growing plants. that is a fact. under many cases. a decent amount of light and c02 can produce a nice balance between c02 and oxygen levels in the water.

to anyone that disagrees with surface agitation.. more power to you. if you agree with film. more power to you.
HOWEVER there are those of us that would prefer to keep plants under higher light levels to get certain colors and or growth rates and also would prefer not to have scum sitting on the top of the tank and have that removed by paper towel every couple of days

in a healthy planted tank with adequate lighting to grow just about any plant and its appropriate color a good amount of c02 will be injected into a tank this can stress fish and the biological filter.. the way around is increasing o2 levels. it does FAR more than relieve stress on fish, or increase pearling
plants need oxygen as well. bio filter needs it to breakdown about 80% of all organics in the tank to usable form by plants or other bacterium this also helps reduce algae as it feeds on ammonia and other organics that plants usually let bacteria make into easier form (plants still prefer ammonia to nitrate though)

wasted c02 is inconsequential to the benefits of added oxygen. there is no research you can provide me with that states otherwise.. my algae problem was due to lack of oxygen i had bba all over the place.. but my fish could barely breath and my plants weren't growing well

i add a sump it wastes c02 and increases oxygen and what do u know bba is showing signs of dissapearing. i've been down ferts roads. raising and lowering c02 levels. trying pumps and blah blah

efficient healthy bacteria and fish come from proper gas exchange.. my DC is still yellow but my ecosystem is far healthier. fish are far healthier and happier

surface film detracts from gas exchange.

low tech tank.. you don't want agitation? no problem. i have one. and when the fitler flow is reduce and the surface stops being broken well and turned over. film starts forming and small bubbles from c02 can be seen collecting i've added c02 and not added c02 on it.. it goes both ways.. the demand isn't high for either gas and it saved on c02 when i used it.. i don't even need it though as its low enough light platns grow fine without c02
its not as important in low tech but again the addition of oxygen is beneficial


as for film. it can be caused by poor filter flow and maintenance. or undersized filtration
it could be the lack of oxygen.. which i forgot to mention also changes redox potential. not as important for the water column but what is going on in the substrate? that plays a major roll in the health of an aquarium
i would suggest a good cleaning of filter media using tank water. siphon some of ur substrate lightly to removed some packed mulm.. don't over do it because it is beneficial to plants

add an airstone at night. it will break up the film and reduce organics in the tank as they will bond to rising bubbles. this will make the rim dirty. keep it clean so u don't have to scrub it off later

allowing the outflow of ur filter to disturb the surface is great for gas and protein exhcange as well. the best way to handle scum is TURNOVER.. u want the water at the top that is rich in oxygen to be pushed to the bottom. this also carries the film back into the water where it will get processed by the filter. it also helps keep the water aerated which we've already discussed as beneficial in anycase. EVEN low tech garners benefits. efficient conversion of ammonia is the best way to prevent algae. period


by the way OP ur plants do look good 
and the bubbles will not hurt anything that way either


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## So_Fishy (Jan 16, 2012)

Thanks for all of your inputs guys! Looks like it was a hot topic. I think the problem arose from a couple of issues now that I step back and think about it. I topped off my aquarium a little more than ususal and it covered the output on my canister filter with water. I think this contributed to the problem. And also I checked my diffuser and the line was loose so I think it was allowing larger Co2 bubbles to form and collect. A combo of these things might have caused my problem. From now on, I'm going to make sure that the output doesn't become fully submerged again because this lessens my surface aggitation. But anyway, yesterday I did a 20% water change, cleaned my filters, repostition my output to give me some surface aggitation and lessened my Co2 output just slightly. And today there are no problems to speak of so far. I haven't noticed any bubbles collecting, film or the white foam. Thanks for all your help! I may add an airstone at night if it continues to be a problem. The timer idea is a good one.


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## rufustfirefly (Nov 10, 2015)

:| I'm still none the wiser after reading all of the replies. Are there no panel of qualified experts here to definatively answer things?


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## natebuchholz (Sep 28, 2013)

rufustfirefly said:


> :| I'm still none the wiser after reading all of the replies. Are there no panel of qualified experts here to definatively answer things?




Does this exist anywhere?


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## kevmo911 (Sep 24, 2010)

rufustfirefly said:


> :| I'm still none the wiser after reading all of the replies. Are there no panel of qualified experts here to definatively answer things?


No.

But Jeff and Blazingwolf knew what they were talking about ...3 1/2 years ago. Ignore the other clowns.


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## Argus (May 22, 2013)

rufustfirefly said:


> :| I'm still none the wiser after reading all of the replies. Are there no panel of qualified experts here to definatively answer things?


You aren't paying enough to expect a panel of experts to be at your beck and call.


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## rufustfirefly (Nov 10, 2015)

I would if there were :laugh2:


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## essabee (Oct 7, 2006)

The problem is caused by certain bacteria and fungi producing slime which accumulates on the water surface of the tank. As long as this flora of slime producers are present the tendency of slime to accumulate will exist and you will see bubbles tapped in it. This slime by itself is not dangerous but if it is allowed to accumulate on the surface it interferes with gaseous exchange and also provides a niche for certain other micro-organisms to proliferate which would turn the slime into a biofilm which will further cut out the contact of the tank surface with the atmosphere and impair all gaseous exchange through it.

The correction of the problem obviously appears to be reduction of the slime producing flora in the tank - but targeting this flora selectively is impossible and perhaps undesirable as they are mostly carrying on very necessary activity in otherwise dealing with undesirable organic accumulations in the tank.

So we are forced to deal with it firstly by generally reducing the micro-flora dealing with organic wastes in the tank by improving the tank hygiene - especially the removal of organic wastes during water-changes by more careful siphoning of the floor and also increasing the maintenance of the filter-system by increasing the frequency of cleaning the media of organic waste.

Next we can deal with the slime itself. The slime accumulates on the surface because it is slightly lower in specific gravity than the tank water and it tends to float - but then it is not that much lighter than water to accumulate on the surface if there is sufficient flow to keep the slime agitated and prevent it from coalescing into large drops and thereby accumulating a higher buoyancy. In CO2 injected tanks the surface agitation is avoided during the CO2 enrichment period - but agitating the surface during rest of the diurnal period is fully possible and this possibility should be fully exploited - so use surface agitators like air bubbles and additional surface-spray by power-heads during this period. Even during the CO2 injection period we can use surface skimmers to draw the slime back from the surface and mix it with the tank water.

It should also be kept in mind that this slime is not something foreign or indestructible - it is mostly proteins and the there are micro-organisms which will exploit it as food - their populations will buildup in your tank with time and the slime phenomenon will disappear.


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