Air Bubbles are bad but sometimes needed?

[The Kapenta Kid]

Reading amother post here I understand that in normal circumstances it is a bad thing to have anything bubbling air into a reef tank.
I had airlines fixed to the venturi attachments on PHs to blast bubbles and oxygen into my tank when I was curing Live Rock in situ. I guess this was the right thing to do. Now the rock is cured and the air is turned off but I have left the now buried airlines in place in case sometime circumstances arise where I might want to strongly aerate the water to deal with some emergency. I assume this is good practice too.

 

[skipm]

The air bubbles don't really do anything for the aquarium, all of the gas exchange (the addition of oxygen) takes place at the waters surface so any king of surface agitation will help promote gas exchange. Lareg air bubbles don't really hurt anything but tiny micro bubbles are a pain since they tend to stick all over the place, make it harder to see things, and can even make your tank act like a big protien skimmer and foam will start building up on the surface. One other drawback to having air bubbles popping on the surface is that they help promote salt creep.

 

[Trogdor]

The air bubbles don't really do anything for the aquarium, all of the gas exchange (the addition of oxygen) takes place at the waters surface so any king of surface agitation will help promote gas exchange. Lareg air bubbles don't really hurt anything but tiny micro bubbles are a pain since they tend to stick all over the place, make it harder to see things, and can even make your tank act like a big protien skimmer and foam will start building up on the surface. One other drawback to having air bubbles popping on the surface is that they help promote salt creep.

I can confirm the protein skimmer effect. I haven't narrowed down exactly where i'm pulling in air but i get a small amount of foam in the corners and around inlet/outlets on my tank. Evaporation will be much higher if you have an air stone too.

 

[The Kapenta Kid]

Thanks for the explanation. I know that air bubblers and the like probably promote more gas exchange by agitating the surface, but I suppose there must be some gas diffusion into water from bubbles or else CO2 systems wouldn't work.

 

[skipm]

I think the reason co2 systems work is due to co2 having somewhat diferent properties than oxygen. There may be a tiny exchange of oxygen in the water but the majority by far occurs at the surface.