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I have read in many places that skimmers are not as effecient at gas excahnge as originally proclaimed. Does anyone have any links/literature on that?
skimmer gas exchange myth?
- Thread starter jmaneyapanda
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Tdwyatt ran the numbers on gas exchange in protein skimmers vs tank and sump surface area and protein skimmers came out way ahead. I didn't phrase that very well but the gist of it is htat the idea behind having to have an open tank for proper gas exchange is phooey.
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My skimmer (Prism) recycles the air (cuts down on noise and acts as an overflow safegard) and as such I suspect cuts down on gas exchange. So I modified it so that it always sucks in fresh air and I think it made a difference. I can't help but think all those tiny micro-bubbles would be the best gas exchange mechanism there is.
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I have read many things that say that Panda. Cameron might still have the links...
Skimmers do not impart much O2 into the water.
Skimmers do not impart much O2 into the water.
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I'll agree with the math.
The second issue relates to gas exchange in the system, and this is definitely directly related to the amount of surface area Vs. the gas concentration in each compartment (surface area, dissolved gasses, suspended gas bubbles). I thought the surface of the tank would be a bigger part of the issue at first when considering sump, display, overflow water falls, and surface agitatin, but in a 180G tank that has a 12 sq. ft footprint (and surface area) and assuming that this same tank has a 6' x 2' sump, the surface area would be 2.2x10^6 (read this as 10 to the 6th power (1 million) or a value of 2.2 million) sq mm of water exposed to air. Assuming that the average skimmer produces bubbles with a diameter of 0.5mm (actually, these are prolly quite large for the average high efficiency skimmer, so this will be a conservative estimate), the surface area of each bubble would be 4(pi)r^2=12.57 x 0.25^2 =0.78 sq mm surface area for each bubble. Assuming 1cubic cm (cc=ml) input = 1 cc foam (ha! again conservative!), and 1 cc of foam has a bubble in each sq mm (conservative est) results in 100 bubbles per cm (100 x 0.78) = 78 sq mm per cc of water flowing through the skimmer. If the skimmer were running at full throttle using a Mag 12 @ ~2 ft head with minimal pipe losses that would be 900 gph = 900 gal/hr x 3785cc/gal = 3.4 x 10^6 cc/hr, multiply that times our figure for the surface area of one cc of water's bubbles (78 sq mm) comes out to 265.2 x 10^6 mm of surface area exposed to air in one hour of skimmer operation, or about 120 times as much more exposure to potential surface gasses from the skimmer than from the surface of the 180 gal tank example with an equal sized sump. Interesting, and that is just one hour...</em> ... using an extremely conservative estimate of the bubble density and large bubble size... Smaller bubble diameter with higher bubble density increase this factor dramatically, conservatively up to 10^5 times...
Of course, this does not take into account the effect of the speed of the air flowing across the surface of the tank and the sump...http://www.thereeftank.com/forums/smilies/biggrin.gif" alt="" /> ...but does consider all the other little things that could be a contributioin to increasing tank and sump surface area, even with extreme surf in either, surface area at best might double... [IMG]http://www.thereeftank.com/forums/images/smilies/rolleyes.gif" alt="" />
With this in mind, tank and sump surface area is insignificant in allowing for gas eschange when compared to the amount of surface area introduced by the skimmer, and the higher the efficiency and the faster the flow rate through the skimmer, the higher the percentage surface area would be attributed to the skimmer's input. This is why it is so important for folks that do have issues with CO2 to use the air intake for the skimmer to introduce outside air (low in CO2 relative to most home interior environments), and the use of an active carbon filter would reduce the chances of introducing some airborne contaminant by this route as well.
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I dont know that this is true. I cant seem to dig up to the article, but there was an experiment where some reputable source measured dissolved oxygen with and without a protein skimmer, an overflow into a sump and returned, heavy aeration at the surface and large air pumps, and the protein skimmer imparted the most dissolved oxygen of the whole lot. The experiment was performed initially to prove that skimmers actually did little to nothing in terms of adding dissolved oxygen, but they found quite the opposite.
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Please do, I am looking for the data, not opinions.
S
soojpudge
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Has anyone hooked up an O2 tank to their skimmer imput before? Or is that just silly? 
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No opinion was stated. It is a fact that protein skimmers add significant amounts of dissolved oxygen into aquariums.
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Ha! Your statment is the defintion of an opinion. What data or facts do you have? That is what I want to see. Not a second/third/fourth hand account of it.
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No, I understand, for sure, I just didnt appreciate the sarcasm and brevity after I spent two hours trying to dig up the article to share and i couldnt find it anywhere. I dont make crap up, i remember the article pretty distinctly, I believe someone actually mentioned it in the second post but i read it more recently so I remembered it pretty well. The only opinion is whether you want to believe im full of crap or not that the study i mentioned actually exists cause i can assure you it does, and to be honest beyond that i dont really care.
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This is a fact buddy. Tell me where the opinion is. Im not gonna get in an argument with you. I was just trying to help you out with your inquiry and you were obnoxious cause I disagreed with you. later.
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I was not trying to be patronizing, I just want to see the data, as I asked in my original post. I am no longer interetsed in anyones second hand stories or accounts of what they read or saw. From anyone. I have had an a$$ full of them in this hobby. It is so filled with misinformation and bad recollection that has warped and taken on a life of its own. For example, how many times have you heard that LPS need lower flow and light than SPS. A BS stament and totally innappropriate in the context of coral care. Yet, it has taken on a life of its own, because of situations like this. Its not at all that I dont belive YOU, its that i dont believe ANYONE!! I make up my own mind.
If you find the article let me know- thanks.
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Where is the fact? Where is the data? Hey- "the moon is made of cheese". That is as much a fact as your statment. Until you or I can show something to prove or disprove, it is merely opinion, is it not?
If your going to being a sensitive person about this, dont try and start things up if you cant back them up.
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I'm cool with that stance and I agree to some extent. But it is a fact that I read an article that said what I mentioned and its up to whomever to make what they will of it. I tried to find the article for a long time so u could do that yourself but I couldn't find it, still I dont feel the infos useless, but I'll try to dig it up again, but I apologize for the misunderstanding, it just seemed kinda condescending to me since I know what I read.
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I appreciate that, and I apologize if that was your interpretation. I didnt intend it, but, nonetheless, I'm sorry. Here is more to my point. I read an article quite recently by a rather well known author who made a claim which I can show is scientifically flawed. It was another one of those reefers "old wives tales" that just goes on and on. This would be in print, but I can show thats its rather full of it. That is why I want to see the info. I dont doubt that you read it, and I dont doubt that this info exists, I just wasnt to see it to determine if I believe it.
Does garlic helps with ick? Many authors (and product manufacturers) will say yes. What does the evidence show? My sweaty stinky sock in the tank will have just as much an effect as garlic- that is the phenomenon I want to discern.
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shut up, jerk.:lol2:
Because theory and reality don't always match. There might be other forces at work that you don't realize, and if you just go working off theory rather than directly measuring what we want to measure, then you can end up very mistaken.
It's like using watts per gallon as a measure of lighting when you really want to use PAR -- by the time you look at bulb age, lighting type, lighting manufacturer, salt creep, reflectors, water depth, water yellowing through dissolved organics, color temperature of your light, the ballast you are using, and whether or not your bulbs are adequately cooled, the actual lighting your system is getting has very little to do with the "watts per gallon" theory.
