does a skimmer provide enough oxygen?

[dido]

Hi all,

I am planning to buy a new skimmer. I was wondering if a skimmer provides enough oxygen in the water to eliminate the air supply in my display tank.

I have so much bubbling going on now that the glass top gets crusty and reduces the amount of light getting into the tank. It would be nice not to have to clean the top glass so much.

Any thoughts?
Thanks in advance.

 

[aquarist=broke]

An air supply in the main tank is bad news. Salt creep will get all your stuff. How about creating surface agitation with a powerhead close to the surface?

As for the skimmer, I think it would kinda help, but surface agitation would really do it.

 

[dido]

I would never have thought that just surface agitation would be enough to provide the oxygen that the animals need. How much agitation should I be looking for? Will it still work with a glass cover on the tank?

 

[Fatal Morgana]

Protein skimmer probably will provide enough air exchange for all your cirtter's need. surface agit. will help breakup the surface scum, but that is not as critical.

 

[Anonymous]

Actually, aquarist=broke (long TIME no see!) is correct. It is only at the surface of the water that the O2/CO2 exchange takes place. Bubbles in the water column do NOT do anything other than agitate the surface where the exchange takes place.

Surface agitation is better achieved with powerheads. A skimmer, while certainly helping with O2 saturation, isn't providing that 'service' via the bubbles, but rather by removing DOCs, which leaves the water less saturated with those and better able to uptake O2. Also, removal of DOCs means that they won't break down in situ, further chewing up available O2.

A covered tank is smart, but not sealed. Otherwise this whole exchange process will be hampered. The same problem exists in well-insulated/sealed homes in colder regions with approaching winter and people/pets inside heated homes.

 

[Anonymous]

Oh yeah, you want to surface to appear well-broken up. Almost 'roiling', like a pot of boiling water, but not so much as to cause a great deal of splashing (which = salt creep).

 

[Fatal Morgana]

Although I agree with you on most of your points, I am still not convinced by your explaination about why protein skimming does not help gas exchange compare to surface agitation. In addition, your following line is a bit hard to understand, and I would like you to rephrase it so that I am more sure of your statement:

...removal of DOCs means that they won't break down in situ, further chewing up available O2.
...

The equation for gas exchange is a bit more complicated than what I am willing to explain in this format, but two of the components are surface area and concentration gradient (O2 and CO2 in particular) Unless I am convinced otherwise, I usually take that the protein skimmer, if sized approciately, provides enough surface area sufficient in magitude to surface area of the tank. The concentration gradient is a bit more complex when you have hydrophobic organic completely surround each of the bubbles, but it should be, in the ball park figure, comparable, if not exceed the amount of gas exchange with surface agitation.

However, this does not mean that I advocate or down play the role and necessity of either surface agitation or protein skimmer in gas exchange, but rather to make sure everyone see both sides of the story, so to speak.

 

[Anonymous]

It is only at the surface of the water that the O2/CO2 exchange takes place.

Surface agitation is better achieved with powerheads. A skimmer, while certainly helping with O2 saturation, isn't providing that 'service' via the bubbles

Each bubble (in a skimmer) has its own surface area, and as suggested above should add up to a sizeable area. The fact that they are in rapid agitation doesn't hurt either.

 

[Deep Blue]

However, water can not be more than its "100%" saturation point.

After that point, additinal "surface area or agitation" provided from the bubbles in a skimmer accomplishes nothing (except for added waste removal via adhesion to the surface of those little bubles of course).

Its safe to say that the water exiting a skimmer is "100%" saturated, but the amount of saturation that adds for the tank is a funciton of the size of the skimmer/flow rate of the skimmer in proportion to the total volume of water.

So....somtimes a skimmer is enough...sometimes it isnt.... its always a factor though.

(newbie speaks....."or somthing like that I think?")

 

[Fatal Morgana]

Its safe to say that the water exiting a skimmer is "100%" saturated, but the amount of saturation that adds in relation to the total volume of the tank is a function of the size of the skimmer/flow rate of the skimmer in proportion to the water volume of the tank..

Good point. But keep in mind that a properly sized skimmer can process several time the volume of the tank in a day. Again, don't trying to downplay either the skimmer or the surface agitation.

 

[Baianotang]

Very interesting I allways thought the the skimmer was enouth.

 

[Fatal Morgana]

Why would you think it is not enough now, Baianotang?