Air bubbler

[Dom274]

Hmmm interesting idea there. What would interest me most about the outcome of this poll would be if there is more than 10% of the reefers out there who use an air pump + wood frit anywhere in their system other than a skimmer. I'd be surprised if more than 10% do this.

I suspect that the evolution of the hobby, through hobbyist interest in "new and better" along with the need of designers/manufacturers to innovate and sell has caused a dramatic shift away from bubbling as a mode of CO2/O2 transport. Additionally, skimmers are very prevalent and can nearly obviate the need for these.

Another question I would pose is: what do you believe we might learn from such a poll? What would it "really" mean if less than 10% of respondents indicated they use an air stone? Does it mean it is not effective? Does it merely represent personal choice, or the power of contemporary marketing and hobby trends?

Skimmers have been all the rage for years now. They're great, don't get me wrong, but if you run a light bio-load its easy to strip the water too clean.

 

[ca1ore]

Because the pH went down. My breath has far more CO2 in it that the air above the sample. That’s how I know it was diffusion from the air bubbles. My understanding of the physics is pretty solid here.

Ah, yes, I agree - misread your initial post (the perils of trying to read posts on my phone). I do agree that bubbles high in CO2 will diffuse into a liquid - that's how a CaRx works after all because CO2 is highly soluble. My earlier point was that O2 is not nearly as soluble so a typical airstone is not going to contribute much if anything to oxygen levels as a result of diffusion. I actually tested this with a DO probe years ago largely to my satisfaction.

 

[Dom274]

Ah, yes, I agree - misread your initial post (the perils of trying to read posts on my phone). I do agree that bubbles high in CO2 will diffuse into a liquid - that's how a CaRx works after all because CO2 is highly soluble. My earlier point was that O2 is not nearly as soluble so a typical airstone is not going to contribute much if anything to oxygen levels as a result of diffusion. I actually tested this with a DO probe years ago largely to my satisfaction.

Get a better airstone, duh. You claim to have tested all this with a DO probe, but you never thought that the airstone could be the issue? You were troubleshooting with a purpose, of course you would find the results you were looking for. The airstone gave me the same .2 bump in PH through the night that my skimmer provides. I don't care about the O2 levels, the point is not to use "house air" high in CO2, and aerate the system as much as possible using the fresh air line.

 

[sghera64]

Ah, yes, I agree - misread your initial post (the perils of trying to read posts on my phone). I do agree that bubbles high in CO2 will diffuse into a liquid - that's how a CaRx works after all because CO2 is highly soluble. My earlier point was that O2 is not nearly as soluble so a typical airstone is not going to contribute much if anything to oxygen levels as a result of diffusion. I actually tested this with a DO probe years ago largely to my satisfaction.

I have to agree with your sentiments regarding the contribution of trying to achieve oxygen saturation. And this difficulty applies equally to a skimmer's ability to correct hypoxia, and to a greater extent it challenges the gas exchange mode of recirculating water across the surface of a DT with power heads alone (assuming no air-siphon aspiration tube in use).

Our agreement on the difficulty in "oxygenating" sea water was preceded by many others. A couple cited below:

Randy Holmes-Farley: quick post I recalled from Mar (see post #2, last sentence): https://www.reef2reef.com/threads/a...ad-why-do-we-skim-it-out.374722/#post-4584659​

Eric Borneman's "The Need to Breathe, Part 3: Real Tanks and Real Importance": Aug. 2005: http://reefkeeping.com/issues/2005-08/eb/index.php
​

Regarding the OP's (@kiwis) original question, the answer is "yes" - a small number of people said that they do use an air stone to affect oxygen transport into tank water (and CO2 out).

The implied question that this thread took off on was: and does using an air stone have much benefit. The answer to how much effect air stones will have largely depends on what else is employed in the OP's system: system volume, what air source (inside house, or outside) is pushed through the stone, how much air and how many stones are you willing to employ, is a skimmer involved (what size), how many power heads reside in the system and how are they affecting surface water agitation, is an algae system used (reverse cycle?), and so on. If many of these are already in use, then adding air stones (or an other power head) will make little difference (law of diminishing returns). If the system has very few of these, they are way undersized, or poorly maintained, an air stone can make a difference. Please reference Borneman's article above Tank#1 v. Tank #2 for the two claims I just offered up.


One other point I'd like to make for those drawing outside air into their skimmer or air stones to reduce CO2 level in tank water (to increase pH): If you have high CO2 levels in your home, then strongly agitating the surface water with power heads, cascading water, or bubbling room air through it actually defeats the objective of reducing CO2. Doing so works to drive the tank water back to a state that is in equilibrium with the household air high in CO2 in stead of towards the intended equilibrium with "lower" CO2 containing outside air. I apologize to the OP if this last paragraph is too far off of your motivation for this thread. I admit I'm reading into your question to anticipate what that intent was.

 

[ca1ore]

If I owned a large Reef it wouldn't need CO2 off-gassing I would control my bio loading and current but I still read it pretty commonly every now and then on the forums. Being on all-electric and not a lot of heavy breathers in home also matters I guess

An observation ..... I have a high bio-load tank (over 100 fish), and that isn't changing anytime soon. I'm also not a slave to the AC system like so many, but even I get to the point were I cannot take the humidity and the house gets all sealed up. With AC on and humans in the house my tank pH falls to about 7.8 overnight; with the AC on but humans on vacation, tank pH falls only to 8.0. So it's the human bioload that's the real problem.

 

[ca1ore]

I suspect that the evolution of the hobby, through hobbyist interest in "new and better" along with the need of designers/manufacturers to innovate and sell has caused a dramatic shift away from bubbling as a mode of CO2/O2 transport. Additionally, skimmers are very prevalent and can nearly obviate the need for these.

Of course .... to both. Other than Tunze, all the early skimmers I can recall (circa. 1986) were limewood air 'stone' driven ..... and they were mostly crap. Many different ways of injecting bubbles almost completely replaced the limewood. Today it's predominantly some variation on the venturi. If I were going to inject bubbles into my sump (I'm NOT), I certainly wouldn't use any kind of airstone, rather an injector like the mazzei.

 

[ca1ore]

One other point I'd like to make for those drawing outside air into their skimmer or air stones to reduce CO2 level in tank water (to increase pH): If you have high CO2 levels in your home, then strongly agitating the surface water with power heads, cascading water, or bubbling room air through it actually defeats the objective of reducing CO2. Doing so works to drive the tank water back to a state that is in equilibrium with the household air high in CO2 in stead of towards the intended equilibrium with "lower" CO2 containing outside air.

Precisely right, and a principle reason why drawing fresh air into the skimmer makes no difference for some. I do it primarily as a way to silence my skimmer, but it has almost no effect on tank pH. That requires exchanging CO2 laden room air with fresh.

 

[Scott Campbell]

Count me in as one who uses air pumps. I have a very heavy bio-load of small creatures and struggled with high levels of carbon dioxide lowering my pH. Air pumps have helped immensely - but I had to leave sanity behind before I saw any benefit. A normal air pump just made zero difference on a large reef tank. I now use three huge air pumps designed for large ponds that all pump simultaneously into my corner overflow. I also use three huge air stones. And I also use CO2 scrubbers on the air pumps. (I don't get salt creep in the corner overflow since the water level is lower.) My pH bumped up just over .1 with each additional air pump and now remains steady at 8.3. The surface area in the corner overflow is rather small and was already turbulent at the surface even before the air pumps. So I am fairly convinced the benefit I am seeing now is from oxygen diffusion. Maybe not - but it seems likely. The corner overflow is basically a constant mass of air bubbles. So I do believe it can be helpful and effective because it has been helpful and effective for me. But again - I had to take everything to a rather irrational and borderline ridiculous level before oxygen diffusion made a noticeable difference.

 

[brandon429]

The best part about those old tank talks from aquatic eco is how they used charts to show how water pumps and power heads (within reason, nobody wants to employ ten more pumps) can't do what you are requiring 3x air pumps to do. Ten million gallon small lake vs reef tank, same dynamics only upscaled

Air is more efficient in every possible way on paper and on limnology web sites if that creep can be contained, and if there's a need. Thats a neat use of air Scott and your findings line up with their taking points for sure. They were more about maintaining maximum fish load and production per unit of volume in their goals so the dynamics carry over well here. I think it's possible that no chart exists showing two water pumps beating a smaller airpump for any form of gas exchange one direction or the other, pH support for us depending on ambient, heat transfer which requires cooling energy in offset, probably five others.

Downsides of laminar current in reefing are less random food distribution and less detritus removal, more pocketing of waste in zones, although laminar flow tends to place it for removal quite predictably given time in the DT. Air is usually a weak form of currents to aid in coral sloughing/sediment rejection but not if it's a 100 gallon air pump ran into a single gallon reef, then it's a hurricane for seventeen years straight.

 

[ca1ore]

Count me in as one who uses air pumps. I have a very heavy bio-load of small creatures and struggled with high levels of carbon dioxide lowering my pH. Air pumps have helped immensely - but I had to leave sanity behind before I saw any benefit. A normal air pump just made zero difference on a large reef tank. I now use three huge air pumps designed for large ponds that all pump simultaneously into my corner overflow. I also use three huge air stones. And I also use CO2 scrubbers on the air pumps. (I don't get salt creep in the corner overflow since the water level is lower.) My pH bumped up just over .1 with each additional air pump and now remains steady at 8.3. The surface area in the corner overflow is rather small and was already turbulent at the surface even before the air pumps. So I am fairly convinced the benefit I am seeing now is from oxygen diffusion. Maybe not - but it seems likely. The corner overflow is basically a constant mass of air bubbles. So I do believe it can be helpful and effective because it has been helpful and effective for me. But again - I had to take everything to a rather irrational and borderline ridiculous level before oxygen diffusion made a noticeable difference.

That's interesting, thanks for sharing. I can certainly see that what you are doing, assuming your house air is not too high in CO2, would be quite effective at removing carbonic acid/CO2 and raising pH. I'd be less confident that it's doing much for O2 levels. Have you actually tested for DO?

 

[Scott Campbell]

That's interesting, thanks for sharing. I can certainly see that what you are doing, assuming your house air is not too high in CO2, would be quite effective at removing carbonic acid/CO2 and raising pH. I'd be less confident that it's doing much for O2 levels. Have you actually tested for DO?

I have not tested for DO. I should do that just out of curiosity. I wasn't especially concerned about O2 levels. I just wanted to stabilize pH.

My assumption, which may be flawed, was that some very small amount of oxygen would indeed diffuse from an air bubble - but that the contact time was so minute as the bubble rocketed to the surface that the effect would be minimal to virtually non-existent. Making the primary benefit of a bubbler surface agitation. But by increasing the volume of bubbles 100 fold or perhaps 1000 fold - total bubble to water contact time started to actually become significant. Since the surface agitation really did not change as I added more air pumps and the upward flow of water did not seem to increase substantially, I have come to assume the difference is oxygen diffusion. But again - just speculation. There was some study I read where the author noted an increase of oxygen in a small 10 gallon tank with a clown fish that made use of a bubbler but no noticeable effect of a bubbler on a large reef tank. His guess was that the bubbler was just too small to make a difference. My experience would confirm the same.

 

[Scott Campbell]

Here is the link to the article - http://reefkeeping.com/issues/2005-08/eb/index.php

 

[ca1ore]

I read reefkeeping religiously and recall that particular article; also remember that I found some of his conclusions curious. Too bad Borneman isn't in the hobby anymore though.

 

[brandon429]

I consider Borneman my mentor for taking time to work with me in private messages at reefcentral, motivated the heck out of me permanently. He's number one proofreader you want shredding articles. his red ink displayed what the real world was all about, too humbling and so awesome. I came on board reefing at a fine time in 01

 

[ca1ore]

Nice! Albert Thiel for me ..... 1987.

 

[brandon429]

bless him x1000 agreed. I have a signed book from him w try and upload pic/its a big deal keepsake Id never part. did you get his book on nano reefs

 

[nycfishy]

Could a battery powered pump serve as a backup during a power failure to keep oxygen in the tank?

 

[ca1ore]

bless him x1000 agreed. I have a signed book from him w try and upload pic/its a big deal keepsake Id never part. did you get his book on nano reefs

I'm sure I have it somewhere; bought most of the reef books before physical publishing went down the proverbial flusher. Met Albert when he was repping for Dupla, before he founded Thiel Aqua Tech.

 

[ca1ore]

Could a battery powered pump serve as a backup during a power failure to keep oxygen in the tank?

Yes, having battery-powered airstones on hand is a very good idea to help in the event of a power failure. I have them, the ecotech batteries and a generator. Nothing could possibly go wrong ........

 

[nycfishy]

Yes, having battery-powered airstones on hand is a very good idea to help in the event of a power failure. I have them, the ecotech batteries and a generator. Nothing could possibly go wrong ........

Any suggestions on a good battery powered airstone that turns on only during a power outage?