Skimming Principles

[jacmyoung]

Sorry the tone of your initial and the follow-up posts made me think you had been tongue-in-cheek. Sorry did not realize you have been in support of my question whole-heartedly from the beginning.

While Puffers offered antidotal evidence that rebuked my initial theory, he did confirm there might be correlation between temperature of the water and skimming efficiency.

The question remains that if anyone had noticed similar change in foam generation rate when their tank temperature had some sudden change.

It is entirely possible even if there is correlation the change would have not made much difference, but I hope it does not hurt to ask the question.

If such or similar question had been asked and answered before, a simple link to that question would have been sufficient. I simply did not see it or may have missed it after reading through all the pages.

As a new comer to the "Advanced Topic" forum, I was surprised of the hostility here. Do I have to show my engineer certificate to participate?

 

[ChemE]

Yes, you need to fax your diplomas (no one with only one need participate) to the forum moderators or all your posts will be retroactively deleted.

I can get on board with the water temp effecting the skimming of certain compounds but need to throw the BS card on the air temp being injected. The thermal mass of the air is extremely trivial compared to the the thermal mass of the water and unless you are injecting supercritical air you aren't going to change the water temperature even locally within the skimmer reaction chamber at all.

The calculation is easy enough and we could go through it if anyone really doubts me but trust me heating/cooling the air isn't going to get us where we want to go.

Please keep posting to this thread; it is one of my favorites on RC right now and I'm checking it daily (at least when FPL sees fit to turn the power on *grumble loudly*).

 

[jacmyoung]

...I can get on board with the water temp effecting the skimming of certain compounds but need to throw the BS card on the air temp being injected. ...

Very well then I'd love to hear your take on water temp effecting the skimming of certain compounds, or if there is a link discuss such thing I'd like to know.

I did not believe cool air would be a magic way to locally cool the water in the skimmer, though I will try when the weather gets cold here. How about a chiller then, will it be enough to cool the skimmer down? Not that I am holding my breadth to see my skimmer start foamming like crazy.

I am very interested in your energy star reef concept, if you can provide a link to such discussion as well?

 

[ChemE]

I'm not aware of any discussion of the solubility of proteins in water as a function of temperature at or near pH 8.3 but it seems reasonable. Many surface chemistry phenomena are strong functions of temperature. I was simply trying to point out that if such a thing were found to be a strong function of temperature we couldn't achieve our target temperture with the air we are injecting.

As to the energy star reef concept, there are a number of good threads here discussing various things. Solatubes have been used successfully by some to light their sps tanks which eliminates the cost of lighting. There is another excellent thread discussing the flowrate through our sumps and the fact that most tend to use far too much. Toss in efficient water circulation by Tunze's and a gravity fed airstone CC skimmer and you're there. With solatubes one could run a tank with a Tunze and an air pump.

 

[barryhc]

Why not try to do the experiment above yourself first, then come back with data to debuke my theory, I thought that was what an engineer supposed to do? At least Puffers offered his own observation first, what did you offer so far?

Quit "chucking spears", and you won't find "yourself" at war. :idea:. . .:hammer:

As a new comer to the "Advanced Topic" forum, I was surprised of the hostility here. Do I have to show my engineer certificate to participate?

I don't have a "piece of paper", I'm working on a forgery to post here! :reading:. . .:uzi:

> barryhc :beachbum: :thumbsup:

 

[Puffers]

Like other materials such as inorganic salts, there is not a strict trend toward higher or lower solubility of proteins as temperature is raised. They can go either direction.

No wonder chemistry is such a mystery to me.... So is it better to have the tank temp in the middle range say 78 deg f to help skim some of both organics? I'm not sure if certain organics are better to target to skim out or all organics. Hmmmmm an organic specific skimmer, wouldn't that be cool.

This may explain in part why certain tanks with corals and very low trates see an increase in coral growth by adding or raising their trates level by a small amount.

The increase in foam production that I have experienced could be and probably was related to other factors; ph, salinity, o2 levels or just in general more "waste" being generated because of the higher temp, ie more stress. I didn't think to test for these things at time, I assumed it was due to the high temp. I should know better by now in this hobby....

Though there might be a correlation between a higher temp and foam. Being the water from the foam could evaporate or drain faster or the air inside the bubbles in the skimmer will rise faster thus getting more water thru the skimmer which in turn fills up the cup faster. Keeping in mind at the time I was skimming more dry so perhaps there is something to this?

I wish I were smart, then I might know what I'm talking about
....

:bum:

 

[Randy Holmes-Farley]

No wonder chemistry is such a mystery to me.... So is it better to have the tank temp in the middle range say 78 deg f to help skim some of both organics? I'm not sure if certain organics are better to target to skim out or all organics. Hmmmmm an organic specific skimmer, wouldn't that be cool.

I expect that some organics skim better at higher temps, some better at lower temps. Overall, I expect it is easiest, if not demonstrably better, to skim at normal tank temperature.

 

[jacmyoung]

I recall reading one early article about skimming principle, when the author theorized higher temperature may excite the molecules therefore reduce there ability to adhere to the surface of the air bubbles. It was a theory also and had nothing to do with solubility.

There appear a great deal of solid matters in the skimmate, I thought if more of the dissolved organics are precipitated out of water they might have a better chance to be carried out by the air bubbles.

 

[Puffers]

Being that it seems that solubility is balanced depending upon the conditions perhaps we need to focus on making the bubbles more efficient.

Maybe we could coat them with a thin layer of calcium (its sticky) or perhaps a gas inside the bubble that somehow does not put everything off balance in the system.

Maybe we charge the ions of the air going into the skimmer to pull out more dirt in the water. Something like an electric air filter. Though I'm not sure even if organics have a polarity or charge. This may be getting into the lines of ozone and I have yet to see any proof that ozone actually increases skimmer performance.


Hmmm after thinking about this and reading my post this won't work. I agree in that if we could dissolve more organics it should result in more skimmate. Though if we think about it, if the skimmer is pulling out large organics then it saves that bioload from the tank already. As Barryhc said, do it before or after.

:bum:

 

[tinygiants]

You have to be careful about filtering. A normal filter catches the material, but it does not remove it from the water column. A skimmer removes the skimmate from the water column. This is a complete export vice just a capturing.

The use of standard filters (floss or elements) require diligent maintenance. Protiens cought in a floss will continue to break down and foul the tank until the floss is replaced.

My 2 cents.
Dale

 

[robsmith32]

oh, the more foam when temp was higher. I would think it could be attributed to the fact that fish metabolism is faster, when the temp is increased, in turn creating more fishpoop faster.

 

[Puffers]

True, but I also think the "poop" will dissolve faster at higher temps making the extra foam in my experience subjective.

There are some items that will break down faster or become more soluble at higher temperatures. I didn't think to check at the time for other parameters to see what impact they might have had, ph, salinity etc.

Happy Turkey Day

 

[duhfactor]

Has anyone ever tried or considered a protein skimmer that ran part or all of the reaction chamber tubes horizontally? I say horizontally, but what I really mean is determining an angle up from level that would allow bubbles to run upward at a desired speed, that hopefully matched the speed of water. You could slow down the travel of the bubbles to give a longer contact time with the water...... In my mind, a design that had low water flow and followed Escobal calculation principles, but was not counter current. I wonder if water could be introduced at the base of the skimmer, and air injected through air stones at points along the skimmer body through "T" fittings similar to plumming clean outs that would allow easy removal of the air stones. A slightly inclined skimmer body could be reversed by adding elbows at the end, and the pipe extended in the opposite direction, then reversed again, etc until you have the legnth desired. I guess space is always an issue, but I think it could work?? I have plenty of room for a skimmer, and plan on building a new one for my 325 gal tank. Any ideas? Here's the thread to my plans...

http://www.reefcentral.com/forums/showthread.php?s=&threadid=713226

Thanks,
D

 

[jacmyoung]

Good thinking, however I would just build several counter-current skimmers if you have room, and place them around the drain chamber in the sump. A large air pump should be able to drive two or three of them at the same time. Skimmer height is critical for retention time.

 

[duhfactor]

When you say "large air pump" which one did you have in mind? I've not looked a great deal at multiple skimmers on the same system, would it be more efficient to run one, then that "skimmed" water fed into the next skimmer, etc , etc. on down the line? Or just two skimmers fed the same water source then dumped as usual back into the sump? I would like to try and get a diagram of the previous "inclined" skimmer design up on this thread to get some more feedback......I'm intrigued by the discussion by "ChemE" and wonder how his thoughts could be tried...


D

 

[jacmyoung]

I'd like to see your diagram as well. I just thought it would be much easier just have multiple skimmers. I have a very small sump, still found room to put three small-size counter-current skimmers in the intake chamber, all driven by an air pump rated for a 100g tank.

 

[tinygiants]

Damon1, your idea seems to be in line with ChemE. It was his suggestion to create the 120 second bubble dwell

My question is does the bubble time in the neck count? It should that bubble is still in contact with the same water as when it started based on the boundry theory that was mentioned.

Dale

 

[duhfactor]

tinygiants,
In my mind,the bubbles in the neck wouldn't count in the bubble dwell time. The reason I suggest not is because the bulk water entering the skimmer body exits prior to getting to the neck typically. I have noticed however that there is a greater concentration of skimmate at the neck compared to the body, perhaps this has to do with reduced water volume at the neck. Do you think a counter current design is absolutely necessary? What do you think about runnung the skimmer body tubes on an incline instead of vertically. Have you built your skimmer yet?

D

 

[tinygiants]

I am still tinkering with my design.

I do not see a problem with inclined tubes as long as the air mix is consistent. To my mind the only benefit of counter current is increased bombardment rate. To that end why would I sacrifice that functionality in the design phase.

Dale

 

[duhfactor]

Very good point indeed.
I wish I knew a formula for determining the ideal bombardment rate. Is it a function of speed, bubble size, impact duration? Man o Man......It seems that from what I'm reading, most people don't think their bubbles stay in the reaction chamber for 120 sec. I wish there were a way to determine exactly what the ideal bombardment rate was, so you could determine if in fact counter current is the best way to go. If so, I suppose it's possible to still build a skimmer with angled tubes from the horizontal to slow down the bubble rise time to 120 sec. If so, maybe then a person could achieve ideal bombardment rate by going counter current, and ideal dwell time for the bubbles via angled tubes, and ideal dwell time for the water flow via appropriately sizing the pump, and on and on and on?? Any thoughts on a good program out there to sketch my thoughts with? What do you think?

Thanks

Damon