water agitation replace air pump?

[cheizy]

Hello everyone, just a quick question.
I think I read somewhere that you don't need an air pump in the tank in order to give o2 to the fish, is this true? I heard that you just need surface water agitation to create O2 in the water. The reason I am asking this is because my air pumps are noisy, and my tank is in my room :help: . BTW I have a rena xp1 and xp3 running with the xp1(jet stream) and xp3 with nothing attached, just free flowing. So my question is, if that I point the outlets toward the surface making little ripples (just enough that no water splash noise is heard), would this be suffient enough for my tank? I have 3 goldies in my 60gal tank. Thanksssssss

[OldMan1947]

I forget the percentages but that is true. The air in your water comes from the surface of the water. That is why a long and wide tank can hold more healthy fish than the same volume tank that is tall and narrow. The figure is like 10 or 15 percent of the air in the water could possibly come from the samll surface area of the bubbles in the water when compared to the total exposed surface area.
The air bubbles perform a rather important function of disturbing the surface so you don't get a surface film. This allows the normal gas exchange to take place at the surface. You can get the same thing by running a filter that circulates the water near the surface. It does not need to drip into the water but needs to stir it enough to keep a film from forming. Most HOB filters will do this quite nicely because of the way they return water to the tank. A canister can be set up to do the same by having the return within a few inches of the surface and discharging horizontally. Even submerged, they circulate the water well enough that unless you set them up to intentionally keep from disturbing the surface, they will prevent any film build up.
I am using an XP3 on my 125 and have the return about 3 inches below the surface. I am using the return fitting with about 8 holes along it to discharge at a slight up angle and my water surface is moving visibly. By itself, it was all I needed until I decided that I liked the bubbles and got an air pump. It can be handy to have an air pump if you need to do something like run a sponge filter but not really needed for the fish to get oxygen.

[Rbishop]

In most tanks, just the surface agitation is sufficeint to supply adequate gas exchange. SOme folks just like the bubbles and some fish enjoy playing in them.

I prefer the bubble look.