Can you ever have too much oxygen?

[Ben K]

Setting up a 20g L tank. right now just have it cycling and all. What I am worried about though is that I may have too much of a oxygen supply form the air stone.

Basically, I have a air bar hidden at the back of the tank, suppling the tank with air. My small 15G also has one of these, tbut the bar is slightly buried. Comparing the two tanks (note the 20G oen has a bigger air pump then 15G) I have noticed that my 20G has a lot of tiny air bubbles floating about. I can surely tell that I have good circulation and all, but I am wondering if all these little air bubbles may harm the fish when I eventually introduce them to the tank. Should I reduce the amount of air being provided to the air bar?

[theotheragentm]

The bubbles you see aren't really dissolving into the water. What they do more so is facilitate in the breaking of the water's surface to allow oxygen and other gases to dissolve across the surface of the water. The only way it could possibly be a problem is if you have a huge amount of air coming through a pump and you're disrupting the water so much the fish are bothered. At that point, you probably wouldn't see your fish through the bubbles.

[Ben K]

Would reducing the air supply to the air bar do any harm then? As right now, the water seems.....trying to find the right word....cloudy? Mainly, with the current amount of air bubbles floating about the tank, I know the tank water will never be as clear as my 15G is, mainly because I have all these bubbles floating about. I'd rather reduce the supply so the air bar is doing it's job, but is causing hundred of tiny bubbles swirling about in the water.

[Atl300zx]

Air wands arent required. There would be no detrimental effects by reducing the air supply.

[QTOFFER]

The tiny bubbles you see are caused by the water 'outgassing'. It's common in newly setup tanks and can take a few days to completely go away.

What happens is pressurized water coming out of your tap is supersaturated with gases - mainly oxygen and nitrogen. In the tank, at normal atmospheric pressure, the gases drop out of solution; hence the tiny bubbles. You will also see lots of bubbles attached to objects in the tank as well as on the glass.

It's also common to notice some outgassing after a major water change.

The airstone will actually hasten the outgassing by breaking up the water surface, but it is neither necessary nor harmful to your fish.

[Ben K]

Originally Posted by QTOFFER

The tiny bubbles you see are caused by the water 'outgassing'. It's common in newly setup tanks and can take a few days to completely go away.

What happens is pressurized water coming out of your tap is supersaturated with gases - mainly oxygen and nitrogen. In the tank, at normal atmospheric pressure, the gases drop out of solution; hence the tiny bubbles. You will also see lots of bubbles attached to objects in the tank as well as on the glass.

It's also common to notice some outgassing after a major water change.

The airstone will actually hasten the outgassing by breaking up the water surface, but it is neither necessary nor harmful to your fish.

Those type of bubbles don't bother me. The bubbles I was getting I know was from the air rod(wand). As after buying a control valve and reducing the amount of air going to the rod, the tiny bubbles swirling around in my tank vanished.

[theotheragentm]

The air the fish breathe is dissolved into the water, so you wouldn't see it as bubbles anyway. The agitation of the surface is what the bubble wands provide, not really necessary if you have a filter return breaking the surface of the water.

[Ben K]

I see. Well, I'll leave the wand in there as I like the look of a bubble wall at the back, as it is positioned between two pieces of drift wood.

[theotheragentm]

Originally Posted by Ben K

I see. Well, I'll leave the wand in there as I like the look of a bubble wall at the back, as it is positioned between two pieces of drift wood.

That's not a bad idea. Some fish even like playing in the bubbles and will swim in and out of the bubble streams.

[Sidi]

I think the only way to get too much oxygen in your tank would be to bubble pure oxygen into it...and I would be worried about fireballs in that case, not fish health.

The other time you may see outgassing is with a lot of plants or algae and high enough lighting that they're producing more oxygen than the water can hold. People with planted tanks often run in those conditions (do a search for pearling to see some images), with oxygen saturated during the day, with no harm to the fish.