# How to increase dissolved oxygen in the tank?



## epicfish (Sep 11, 2006)

Point a powerhead the surface to get a bit of surface movement. Crank up the CO2 a tiny bit to compensate for any outgassing.


----------



## gloriabills (Oct 4, 2005)

Here's what I just read about Corys in Aquarium Fish International magazine.

Air gulping: Like all catfish, Corys have a modification of the gut that allows them to extract oxygen from swallowed atmospheric air. This allows them to survive where other fish would suffocate, due to low oxygen content in the water. However, evolving this use for their gut has made them dependent on atmospheric air. Their gills cannot extract enough oxygen from the water to meet their needs - and without access to the atmosphere, they will drown.


----------



## moogoo (Dec 7, 2007)

I would set up a timed powerhead or airstone to go at night. At the same time, have the CO2 shut off with a timer too. Plants take in O2 at night, so any CO2 you add at night is not even used.


----------



## spypet (Sep 15, 2006)




----------



## mistergreen (Dec 9, 2006)

gloriabills said:


> Here's what I just read about Corys in Aquarium Fish International magazine.
> 
> Air gulping: Like all catfish, Corys have a modification of the gut that allows them to extract oxygen from swallowed atmospheric air. This allows them to survive where other fish would suffocate, due to low oxygen content in the water. However, evolving this use for their gut has made them dependent on atmospheric air. Their gills cannot extract enough oxygen from the water to meet their needs - and without access to the atmosphere, they will drown.


interesting.. Very much like bettas and gouramis.


----------



## daFrimpster (Mar 7, 2005)

spypet said:


>


These are interesting, SpyPet. Have you tried one yet? I am getting ready to setup a stream type tank and one of the requirements is high dissolved O2 levels. I might try a couple of these.


----------



## swylie (May 10, 2007)

gloriabills said:


> Here's what I just read about Corys in Aquarium Fish International magazine.
> 
> Air gulping: Like all catfish, Corys have a modification of the gut that allows them to extract oxygen from swallowed atmospheric air. This allows them to survive where other fish would suffocate, due to low oxygen content in the water. However, evolving this use for their gut has made them dependent on atmospheric air. Their gills cannot extract enough oxygen from the water to meet their needs - and without access to the atmosphere, they will drown.


I'm not buying it. I rarely see my cories do this, if ever. They'd have drowned long ago if this were strictly true.


----------



## spypet (Sep 15, 2006)

daFrimpster said:


> These are interesting, SpyPet. Have you tried one yet.


I love mine. I have both the large and small. the small makes a great Co2 diffuser/mister while the large is preferred for O2. they are very quite, and make bubbles that are even finer than any air stone. if you already have 3" of substrate, they hid much better than some ugly power head. the only downside is I would not use them with a sand substrate. if you don't need the LED, don't get it, cause it's bulky with the ario. even if you think you might like it later, Hydor now sells the LED's separately, so there is no need to get the bundle. Hydor also has great customer service - they replaced a unit I complained was too noisy at their cost.


----------



## bgoodwins (May 3, 2007)

I've seen mine gulp in a non-CO2 tank before.


----------



## dekstr (Oct 23, 2007)

mistergreen said:


> interesting.. Very much like bettas and gouramis.




Haha I don't really buy that either. If the corydoras were solely dependent on surface air, then they're no different from a swimming land animal in terms of respiration.

However, my fish are slowly dying for some reason.
Rummynose tetras are gasping really hard and some are near the surface for some reason. One dead loach. Other corydoras are going to the surface for air as frequently anymore, but their breathing is extremely rapid. Only ones that seem fine are pearl gouramis. AHHHHHH!

I turned off the CO2 for now and hope that will help.

I am also suspecting some of kind of disease. I bought 18 white cloud minnows for another tank a few weeks ago and they all died really quickly. Same symptoms happening to my fish in the main tank right now. Something must have somehow cross-contaminated and now my fish in the main tank are dying.


----------



## swylie (May 10, 2007)

It could be a bacterial gill infection. I had some zebras die before I figured out what was going on, and the symptoms were lethargy, red gills, and rapid breathing. At least, I think it was a bacterial gill infection, you can never be sure. I know that adding an antibiotic (Maracyn II, minocycline) stopped the deaths.


----------



## dekstr (Oct 23, 2007)

Hey swylie, 

Thanks for the info. I'm still stumped on this.

My weapon right now is patience.

This morning, symptoms Swylie mentioned were dead-on, rapid breathing, lethargy, (but red gills is impossible to tell with rummynose tetras :icon_roll ). Some were even losing equilibrium and flipping over a bit.

Anyway I immediately cut off the CO2 (it's DIY btw, sorry for not specifying at first). I had to go to school so there was nothing more I could do other than not do anything to make it worse.

I come back at 6pm, and the fish are fine! Schooling again. Swimming around. So now I'm starting to suspect CO2 imbalance. Need to test pH and KH changes soon.

So far I've added an airstone near the water surface and that's it. Stopped feeding today. 

The water is starting to become cloudy white. Wondering what's going there.


On a side note: Don't throw your fish into your backyard! I threw out a dead loach yesterday morning. Last night a giant raccoon, I say the size of a large dog, dropped by. I looked at it, and it stared right back for about 30 seconds. I swear suburban raccoons get bigger and bigger and more and more fearless.


----------



## shwerm601 (Dec 16, 2007)

Ive got a submersible c02 diffuser that came with my DIY c02 setup I got at a LFS. At night I unplug the hose from c02 supply and let it diffuse oxygen into the air. Fish seem to like it very much. Just a suggestion because the diy c02 kit was about 20 bucks so Ive got it prebuilt looks good and the submersible diffuser was a nice added bonus. If you got a powerhead though turn on the are at night and powerhead do just fine to disturb surface.


----------



## moogoo (Dec 7, 2007)

Hey dekster,

I had similar issues in my 10 gal. with DIY CO2. I now run an airstone at night starting 2 hrs after lights out and ending two hrs before lights on. I run my lights for 10 hrs a day. When I first added the CO2, my fish were breathing rapidly but not coming to the surface and gasping. But I was still concerned so I started the airstone routine. Now when I look at them, they are completely fine. Normal breathing and behavior. Definitely helped with the airstone. Because of this, in my 30 gal, I plan on setting up a hydor ario to run at night after lights out. Co2 will be cut off via solenoid and timer and the ario will run to oxgenate the water at night for both the fish and the plants. From what I've read from others experiences, the ario is very efficient, very quiet and easily hidden. I've got a perfect spot for it already


----------



## dekstr (Oct 23, 2007)

Thanks for the comments.

I added an airtstone just beneath the water surface on a separate timer.

It runs an hour before lights til right before lights turn back on.

A really dramatic improvement from the fish now. 

So now I have 3 timers, 1 for moonlights, 1 for regular daylights, 1 for airstone.

Another way I thought of is to plug the powerhead diffusor to the daylight timer as well. I just need an exit for the trapped CO2.


----------



## myhui (Jan 17, 2008)

How about adding a biowheel filter like the above? The wheel lets atmospheric CO2 and O2 diffuse into the water naturally.

It also creates surface current if you adjust the water height just right to get some splashing as the filtered water is dumped back into the tank.


----------



## dekstr (Oct 23, 2007)

myhui said:


> How about adding a biowheel filter like the above? The wheel lets atmospheric CO2 and O2 diffuse into the water naturally.
> 
> It also creates surface current if you adjust the water height just right to get some splashing as the filtered water is dumped back into the tank.


I could, but the biowheel also lets out excess CO2 in the tank, which is counter-productive.

I have an airstone running at the moment. Surprisingly, it has solved all my fish-health problems. 

Good idea for a non-co2 injected tank though!


----------



## Raul-7 (Oct 17, 2003)

swylie said:


> I'm not buying it. I rarely see my cories do this, if ever. They'd have drowned long ago if this were strictly true.


They have the ability to, but not necessarily the need.


----------

