# not enough oxygen...



## joeydee (15 Feb 2011)

Hi 

Ive got a question thats been bugging me for a while now. Ive got a planted tank and recently introduced some fish and notice that it is suffocating from a lack of oxygen. CO2 diffuser is in place but was advice that surface agitation will release CO2 within the water at the same time surface agitation is needed to increase the oxygen for the fishes.
My current air pump has only an no/off option so i thought ill head out to get an Eheim air pump 100 since it comes with an adjustment but still didnt make much of a different as it makes too much bubble and noise. There goes $75AUD.

So i thought my best option at the moment is to increase the water flow from the Fluval 205 to get a little surface movement going to possibly increase the oxygen in the water.

Does anyone have any other solution that maybe i could try to increase the oxygen at the same time minimise the noise of the bubble and maintain as mush as possible the amount of CO2 in water?

Tank size: 1 and a foot - 10G
Light: 2 x 24w HO

Thanks in advance


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## foxfish (15 Feb 2011)

You dont give quite enough info about you C02 system, is it a pressurised system?
Anyhow forget the air pupm & aim for a really good water movement withing the tank, you need a filter or powerheads that are rated to offer 10 x the tank volume.
This type of flow will give good gas exchange & help to distribute the C02 evenly around the tank.


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## Anonymous (15 Feb 2011)

Lack of oxygen or an *ammonia* spike?

Cheers,
Mike


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## Gfish (15 Feb 2011)

What!? Ammonia spike!? What made you suggest that????

Hi,
I have given this alot of thought and it's something that isnt a problem for most planted tank enthusiasts because   most folks tanks have masses of green and a low stock of small fish. In this situation the plants do produce enough oxygen in that environment for the amount of fish in there.

However, take my big tank for example. It has quite alot of plants but they're all slow growers and most are high in the tank on bogwood, way above where the majority of my fish are. The lemon tetras seem to be fine, but the bottom feeders, well they do breathe heavy when CO2 injection level is at it's highest. I have tried a few things to get more oxygen into the water, and the Eheim air pump was too noisy for me and the bubbles too big so most rose to the surface even when placed infront of the output. 
I'd like to know how folk have achieved high oxygen and CO2 together. 
The best method for increasing oxygen for me without disturbing the surface too much has recently been to have the output pipe from one of my filters half in, half out of the water so it pours in and pulls air bubbles in with it and around the tank. I'm sure I lose some CO2 but not too much. The drop checker reading hasn't changed too much. 
My other filter comes in via a long spraybar which has the Co2 charged water entering the tank this way. I have it pointing slightly upward so it moves the surface.
My tank looks to have alot of surface movement and a little actual breaking where the other pipe comes in as described. So I think this is as good as it gets with what I have. But I'd love to hear how other folk have achieved
the optimum O2 and CO2 levels.

Cheers

Gavin


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## Anonymous (15 Feb 2011)

When introducing fish for the first time in an aquarium there's not enough bacteria in the filter to process the ammonia released by them or the tank was not fully cycled but of course there can be high levels of CO2 that's causing it or some sensible little dudes. You need to test both ammonia and CO2 to know for sure what's causing it, do a water change, aerate heavily and when it's alright stop the aeration and slowly increase the CO2 levels and keep it lower than before.

Don't stress yourself about oxygen in a mid-high planted tank it's usually more than enough even at high temps an low water surface movement if the plants are healthy (had 35 degrees last summer and all fishes were alright, no aeration needed).

Cheers,
Mike


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## ceg4048 (15 Feb 2011)

joeydee said:
			
		

> Hi
> 
> Ive got a question thats been bugging me for a while now. Ive got a planted tank and recently introduced some fish and notice that it is suffocating from a lack of oxygen. CO2 diffuser is in place but was advice that surface agitation will release CO2 within the water at the same time surface agitation is needed to increase the oxygen for the fishes.
> My current air pump has only an no/off option so i thought ill head out to get an Eheim air pump 100 since it comes with an adjustment but still didnt make much of a different as it makes too much bubble and noise. There goes $75AUD.
> ...


Hello,
    The symptoms being experienced by your fish is not due to lack of oxygen in the water column. It is due to the loss of oxygen carrying capacity of their hemoglobin due to excessive CO2 in their bloodstream. You simply are injecting too much CO2 for their bodies to deal with. Excessive CO2 in the water prevent the fish from evacuating CO2 from their blood. Elevated blood levels of CO2 lowers the blood pH which then causes the hemoglobin to lose it's affinity for Oxygen.

The fish attempts to remedy this situation by adjustments to circulatory and other systems which would normally increase Oxygen delivery to the tissues. However, increased gill ventilation is unlikely to improve blood oxygenation to any great extent, and neither does adding surface agitation, which actually lowers water Oxygen content (although this also lowers CO2 giving the illusion that more oxygen has been made available).

During the day, plants produce oxygen and, by so doing, increase the oxygen level in the water more than could be achieved by surface agitation or bubbles, which simply releases both CO2 as well as Oxygen from water to atmosphere.

The strategy of surface agitation and air pumps works well at night to outgas CO2 from the water, and to introduce Oxygen during a time when the plants are not producing Oxygen but are strictly consuming it, and in so doing are actually competing with the fish.

During the day however, it is a better strategy to lower your CO2 injection rate and to have better flow and distribution patterns inside the tank which then delivers the CO2 to the plants with better efficiency and which also will do a better job of delivering oxygen to all parts of the tank.

If you have 54 watts of T5 over a 10 gallon tank, then this could require such high levels of CO2 that it then becomes toxic to fish. Lowering your lighting intensity will reduce the requirement for CO2 and will therefore lower the stress unilaterally.

Cheers,


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## ceg4048 (16 Feb 2011)

Here are a couple of YouTube videos. If you watch them in sequence. Of course they discuss Oxygen and CO2 transport in human blood, but it's a very similar process in fish. The obvious difference being gas transport across lung tissue versus gill tissue, however, that's just a mechanical difference. The chemistry is very much the same.

The basics of gas transport. The terms PO2 (Partial Pressure of Oxygen) and PCO2 (Partial Pressure of CO2) refer essentially to "Oxygen concentration" and "CO2 concentration" respectively.


This is an excellent animation of the blood cells describing the basics of the Iron containing protein Hemoglobin.


These are 6 parts of a discussion of gas transport by Dr. Najeeb. He's giving a lecture to medical students about CO2 transport, but laypersons like ourselves can at least get a clue of what's going on inside a fishes body when we change the pressures of the gases externally.


Cheers,


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## joeydee (1 Mar 2011)

A big thanks to all the advices and tips!

So far ive dropped my bps to 1 and raised my outlet closer to the top (water surface) and change my lighting from an HO back to just a normal 24w also dropping the duration from 12hr to 8-10. The fish are doing better than ever, plants are growing a bit slower and algae are going crazy. i guess i just havent found that perfect balance between the lighting, oxygen and co2 in my tank yet. Apart from the algae (which i dont think its a big deal) everything is a-okay.

i know oto and sae will never win the war against algae but until i find the perfect point these guys may have to help me out with the cleaning.

As ive learnt the hard way, it is indeed hard to keep nice plants (that require co2 + lighting) with nice fishes.


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## roadmaster (1 Mar 2011)

joeydee said:
			
		

> A big thanks to all the advices and tips!
> 
> So far ive dropped my bps to 1 and raised my outlet closer to the top (water surface) and change my lighting from an HO back to just a normal 24w also dropping the duration from 12hr to 8-10. The fish are doing better than ever, plants are growing a bit slower and algae are going crazy. i guess i just havent found that perfect balance between the lighting, oxygen and co2 in my tank yet. Apart from the algae (which i dont think its a big deal) everything is a-okay.
> 
> ...




I believe it hard sometimes to tell what one thing may or may not have achieved the desired result's when three or more factor's are adjusted at one time.
Is to me, similar to those who use shotgun approach when treating sick fishes with medications. They may try three, or four medications in a short period ,sometimes without treating with one med for full course of treatment, and if the fish improves, (seldom happens with this approach) they are left wondering what one medication or combination of same, brought relief. Most often though, they aren't sure what particular pathogen,prasite they are dealing with  hence,,the shotgun method of treatment.
Maybe simply adjusting one element such as CO2 rate, and then observing (in this case the fish), one can easier identify what factor was or was not at play,Then move to the next ? Lighting intensity,fert dosages. This would be  my approach anyway, opinions vary .
 Perhaps an ammonia or nitrite spike would not register as such, if tank was heavily planted and few fishes were present, but could also maybe be something to consider if canister filter is particularly dirty, and  bacteria therein were being starved of oxygen.
Maybe this factor too could easily be eliminated by more frequent filter maint?
I realize that the only things that happen quickly in the aquarium are usually bad things ,and with CO2 injection that bad things happen more quickly, But maybe trying one thing at a time and observe the result's would help identify the root cause of problems and give one a better idea as to the way forward? IMHO


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## dw1305 (1 Mar 2011)

Hi all,
This is quite a complex area, and something that is a problem for a lot of non-planted aquarists.  So with the traditional apologies for cross-posting, but I wrote an article for another forum that should be available and may be of use - "_Aeration and dissolved oxygen in the aquarium_": <http://plecoplanet.com/?page_id=829>

I think Clive's post covers it pretty well. The only other issue I can think of is that CO2 is much more soluble in water than oxygen. 





> The strategy of surface agitation and air pumps works well at night to outgas CO2 from the water, and to introduce Oxygen during a time when the plants are not producing Oxygen but are strictly consuming it, and in so doing are actually competing with the fish. During the day however, it is a better strategy to lower your CO2 injection rate and to have better flow and distribution patterns inside the tank which then delivers the CO2 to the plants with better efficiency and which also will do a better job of delivering oxygen to all parts of the tank.


If you don't mind your CO2 out-gassing, and based upon our work with landfill leachate, a "wet and dry" trickle filter is the best option for enhanced oxygenation, it has a very large gas exchange surface and this means that they are very efficient at biological filtration (and the conversion of ammonia to nitrite and nitrate is an oxygen intensive process as "roadmaster" noted). I think "plantbrain" is now using them but I'm not sure if he is using a sealed sump, so Tom if you are out there?

cheers Darrel


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