Enough Gas Exchange?

Ryan · #1 08-30-2009, 04:20 PM

Rippling the surface does nothing for gas exchange, there has to be a break in the water for proper gas exchange.

intarsiabox · #2 08-30-2009, 04:38 PM

I only have an Aqua C Remora at the moment so I don't know if this gives me a lot of O2 into the water. The sump itself would stay open top.

Myka · #3 08-30-2009, 04:40 PM

The Remora should do a fine job. It uses a spray injection for the bubbles, and it creates quite a few. I shouldn't think you would have any issues. If you do, blow a small fan on the skimmer so it gets more fresh air.

Oxymoron · #4 08-30-2009, 05:01 PM

Quote:

Originally Posted by Ryan

Rippling the surface does nothing for gas exchange, there has to be a break in the water for proper gas exchange.

Correct me if I'm wrong but I was under the impression that surface agitation created by powerheads helps break up the film on top of the water for filter's to pick up.
Breaking this film in turn creates a larger surface area for gas exchange to occur.

Ryan · #5 08-30-2009, 05:08 PM

Yes but there has to be a break in the tension of water for the air to mix into the water. This is why airstones work so well. There are so many bubble breaking the surface of the water helping with gas exchange.

One question that hasnt been asked is what stocking levels do you have in the tank? How big is the tank?

Oxymoron · #6 08-30-2009, 05:15 PM

After reading your first post I spent some time researching the matter.
From what I've found, the general consensus seemed to be that airstones are one of the poorest forms of gas exchange as the surface area of the tiny bubbles are so small.

Ryan · #7 08-30-2009, 05:17 PM

There is going to be more surface area in 1000 1ml air bubble there there is on 1 1000ml air bubble. Surface area is what you want with oxygen exchange. Why do you think skimmers have millions of little bubbles instead of a few big bubbles? Because there is more surface area.

Oxymoron · #8 08-30-2009, 05:41 PM

I believe that airstones in a reef tank are unnecessary and not needed as long powerheads are positioned to continuously roll water from the bottom of the tank to the top. Your dual overflows and the use of a skimmer should be more than enough. Airstones can also introduce micro bubbles in the display which are unhealthy for the fish. And there's also a build up of salt creep from the spray they create. Hope this helps. Others may have other opinions as this is a topic that has been argued about many times lol.

Myka · #9 08-30-2009, 06:10 PM

Airstones rarely have a place in a sw tank, but they can make a big difference in raising pH by off gasing CO2.

Both Ryan and Oxymoron are right. The rippling of the water surface does break the layer of greasy organics on the surface, however if you have a sump with an overflow the surface grease should not be an issue. An airstone does increase O2 in the tank (the efficiency of this varies with the quality of the airstone and how fine the bubbles are), but if you are running a skimmer (that fits the size and bioload of the tank well) a skimmer is essentially a giant airstone when it comes to O2 and CO2 gas exchange. If you are using cheapie $2 airstones you aren't going to produce much O2 exchange. Buy some super fine wood or glass airstones, and the results will be much greater.

Snaz · #10 08-30-2009, 06:45 PM

Quote:

Originally Posted by Oxymoron

Airstones can also introduce micro bubbles in the display which are unhealthy for the fish.

I think the accepted consensus on this point is that it is false. Micro bubbles occur in nature, crashing waves on a reef, with no ill effect.
http://www.reefkeeping.com/issues/2004-01/eb/index.php