Filtration And Oxygen

[kfitzgerald22]

Good Afternoon,

I have had a 55 gal (US) aquarium running for about 3 years now. It currenly has about 20 fish and is well under capacity. I have one bio-wheel external filter that is rated for 40-70 gallons, and I just added a second that is rated 30-50 gallons.

I also have an air pump that releases o2 at the bottom of the tank. Since adding the second filter and aerator I have noticed that some of my fish arent as lively as they were before.

Is it possible I am pumping too much oxygen into the water? Is there a way to better regulate or monitor this?

Any help would be appreciated, I am looking to add a few more fish to my community soon however i want to make sure that the tank is ready for them.

 

[dthoffsett]

I doubt you have too much oxygen in the tank, when my mbuna tank was set up I overfiltered it far more than yours (which is quite common in cichlid tanks). I'd be more concerned with ammonia or nitrite levels. Have you tested your tank recently? If so, what were the readings? Iif not, you should test it.

 

[Rooster]

Good Afternoon,

I have had a 55 gal (US) aquarium running for about 3 years now. It currenly has about 20 fish and is well under capacity. I have one bio-wheel external filter that is rated for 40-70 gallons, and I just added a second that is rated 30-50 gallons.

I also have an air pump that releases o2 at the bottom of the tank. Since adding the second filter and aerator I have noticed that some of my fish arent as lively as they were before.

Is it possible I am pumping too much oxygen into the water? Is there a way to better regulate or monitor this?

Any help would be appreciated, I am looking to add a few more fish to my community soon however i want to make sure that the tank is ready for them.

VERY common misnomer... an air pump DOES NOT add oxygen to the water !!!! (well, to be pedantic, it will add a minute amount - certainly less than can be measured !)
Its movement of the water at the surface that allows an exchange of gasses...
Could be that you DO have too much water movement... but certianly not "too much O2" - some fish like a quieter life

 

[Corleone]

If you turned off the air pump, you'd probably get no difference in oxygen levels. The bubbles aren't in contact with enough water to really make a difference, however they do help create surface movement, which is good for gas exchange - most power filters do this on their own.

With light surface movement, chances are you're probably going to be saturated with oxygen anyway - you really can't go too high, since there's a limit to how much the water can hold. A planted tank can suffer from too much gas exchange, but that's more from too much CO2 leaving than too much O2 entering (and not the fish that show ill effects for it). Lack of oxygen causes fish to gasp at the surface (this can also be caused by nitrite in the water of any one of a great many diseases effecting the gills or the blood's ability to take in oxygen).

Any change in water chemistry? What's your water change and general maintenance/testing routine? Also, a change in temperature can do it - some of my fish are a bit more active in the winter than they were over the summer, others are much more active when it's hot.

What fish do you have? It could also just be age, as 3 years would put some species in their declining years, particularly if you buy them closer to adult size to start with.

 

[OldMan47]

So one more person to say it's not an oxygen issue KFitzgerald. What you may have done is put so much water flow into the tank that the fish have no calm place to swim so they are hiding in a quiet spot. Even the bubbler will move a lot of water if it has a good flow rate.