New Skimmer – Price is no Object!

[hahnmeister]

I dont think skimming is so much about removing the yellowing compounds as preventing them. Sure, ozone can clear your water, but regular air... I think its more about removing organic matter before it goes through the nitrogen cycle. The conversion to nitrate by bacteria is what produces phosphates and the yellowing compound. So by removing the source, you are removing the potential. At that, almost any protein or nutrient that one of these bacteria can convert is capable of yellowing the water. So in the end, the idea of testing skimmers based on how tinted the water is is rather sound, as long as you take away the capability of live rock to digest from the equasion.

 

[pjf]

I think the current thinking is that for some proteins, 2 minutes of dwell time is necessary to bind with a bubble (http://www.hawkfish.org/snailman/skimmer101.htm). With a co-current skimmer perhaps height is necessary. On the other hand, a counter-current skimmer may be able to provide long dwell times with a shorter height.

I believe that there are many counter-current skimmers available but they are not marketed as such. Hahnmeister recommended a 22-inch skimmer, the Turboflotor 5000 Shorty (http://www.aqua-medic.com/turboflotor_5000_shorty.shtml) that promises long dwell times but the phrase, “counter-current,” is not in its description. Other “counter-current” skimmers include the relatively short recirculating skimmers.

There is a lot of anecdotal information about skimmers being able to remove Gelbstoff but I’ve yet to hear confirmation. Perhaps these skimmers used to be marketed but are no longer in the vogue.

 

[pjf]

Even if skimmers cannot remove Gelbstoff completely, an objective of improved skimmer performance should be the removal of more soluble proteins. Should the removal of the "source" of Gelbstoff be the objective, we still lose nothing by striving in this same direction.

You are correct that removing interferences, such as bacteria and live rock, is important. This is the reason why trying to analyze skimmate is like trying to analyze a "moving target." The bacteria in skimmate starts to degrade it as soon as it is collected. It is much easier to analyze the aquarium water column.

Here is a quote from Habib:

<a href=showthread.php?s=&postid=10673417#post10673417 target=_blank>Originally posted</a> by Habib
Generally speaking testing of skimmate is not a easy task and linking test results to skimmer efficiency can be very tricky.


Skimmate consists of a water phase and all sorts of particles. Many of the particles being organic and many of them living.

Skimmate's environment is totally different from the aquarium so it can boost the growth of certain bacteria and algae in the skimmate.

They will change the water chemistry rapidly, taking away chemicals, transforming them to something else and excreting chemicals in the skimmate water.

So its is a chaning environment and might not reflact the chemicals in the tank.


Probably the closest to measuring the skimamte might be by digesting the full sample chemically and have it measured for phosphorous, nitrogen and carbon.

Same would have to be done with a tank water sample.


Would it say something about skimmer efficiency? Not in all cases because what is the definition of skimmer efficiency?


Talking specifically to the organcs test, the color of the skimmate will highly confound the test. Besides what phase would be emasured? water only or also the surface of particles? If surface of particles as well then the skimmate would have to be mixed completely making a huge mess and samples would not be representative.

Even if there was no color to the skimmate and if it would be perfectly clear how would one know that the composition was not altered by the organisms living in the skimmate?


Skimmate is a complex thing to measure and has a rapidly changing chemistry, the redox value of skimmate changes rapidly as well.

(http://www.reefcentral.com/forums/showthread.php?s=&postid=10673417#post10673417)

 

[GuySmilie]

Iodine Numbers & Molasses Numbers

Iodine Numbers & Molasses Numbers

This is becoming an interesting discussion.
Maybe a closer look at carbon's beneficial properties would lead to a more practical way to test efficiencies of a protein skimmer. Since Gelbstoff is the subject of concern, and carbon is the most popular medium to extract it from the water column, I snooped around a bit today and found this tidbit about 'iodine' and 'molasses number':

"Iodine is the most common standard adsorbate and is often used as a general measurement of carbon capacity. However, because of its small molecular size, Iodine more accurately defines the small pore or micropore volume of a carbon and thus reflects its ability to adsorb low molecular weight, small substances. Iodine number is defined as the milligrams of Iodine adsorbed by one gram of carbon, and it approximates the internal surface area (square meters per gram)."

"Molasses number is a measure of the degree of decolorization of a standard molasses solution. Because color pigments are large and cannot penetrate into small pores, the molasses number defines the large pore or macro pore volume of a carbon. It is used as a relative guideline for measuring the capacity of a carbon for larger adsorbate molecules."

Reference site

I don't know what 'molasses numbers' are all about, but instinct tells me that it's some sort of index used to scientifically define the clarity of molasses. Maybe that process can be utilized to measure seawater clarity as well, since the carbon folks tend to cite it often.

I know even less about chemistry, but according to this quote, maybe an iodine test can extrapolate data for measuring how well a skimmer removes low molecular weight matter.

Just food for thought....

 

[hahnmeister]

pjf, there are some 22" tall skimmers that I feel are 'enough' but dont get me wrong... I would rather just have 6' skimmers. The reality is that for many they just dont have the room under the stand. The turboflotors shorties are 24" tall, but the shorty2 model is 3', and the baby (my cousin uses one) is about 4'. The single and twin are 6' tall... and they are definately counter-current. The inlet is towards the top, and the water flow is downwards to the bottom... all the way coming into contact with a storm of bubbles coming up from the bottom.

But for all the reasons I see, and we have come up with, thats why I said that the only way to compare skimmers would be to set them up side by side on a very large system and see which one collects the most skimmate (condense the skimmate, and maybe even analyze it). One skimmer could collect just alot of one type of proteins though... enough to make it seem like a champ perhaps... but another may collect less overall, but a wider variety of DOC's (more air and shorter vs. taller and less air speculation). This is where skimmate analysis by the likes of Dr. Borneman comes into play.

http://forum.marinedepot.com/Topic52254-9-1.aspx

 

[BeanAnimal]

Hahn... lets take one step back and answer a key question.

Is it better to (using your wording) just collect a lot or to collect a wider variety?

We do not know the answer, even if we CAN determine exactly what is in the skimmate and how much each model of skimmer produces of each type of "stuff".

Thus folks like Habib use phrases like "moving target" or "what is the definition of skimmer efficiency".

So we come full circle

Can we possibly determine WHICH proteins are yellowing and then use the testing to choose a skimmer that excels at removing those proteins vs other proteins? I guess. The process still begs the question, is it worth the trouble?

As you have mentioned, if we could all have 14' tall skimmers than the point would be rather moot, if not bring up other questions.

If the skimmer is THAT good at removing everything, then is it possible to overskim? I.E. would removing the yellowing compounds been better achieved by CARBON, while letting the lesser skimmer do a better job on the other compounds?

Is it worth all of this trouble to try and do away with carbon? What other benefits are we possibly losing from ditching the carbon?

 

[hahnmeister]

Well, it might be interesting at least. Borneman finds it interesting enough to study. Im not saying a skimmer could take the place of carbon anyways, just that it might be nice to clarify some concepts, and differences in opinion with an objective test.

 

[BeanAnimal]

Ohh I agree it is interesting. I just wanted to make sure that we keep a perspective on what we are talking about. Interesting and useful are not one in the same

BTW: I was not proposing that what you said was wrong or off base at all.

 

[hahnmeister]

Hey, its a hobby after all... doesnt have to make sense or be profitable... lol... not in this hobby.

 

[pjf]

Promiscuity or Fidelity?

Promiscuity or Fidelity?

<a href=showthread.php?s=&postid=10640279#post10640279 target=_blank>Originally posted</a> by manderx
a tall countercurrent will produce the cleanest effluent. biggest problem with them is they have to be huge for the amount of water you push through them, otherwise all that water flowing down against the bubbles causes too much turbulence which then defeats the whole idea of true countercurrent flow. bubbles start off clean at the bottom and are exposed to cleanish water. then as they rise, they get dirtier and dirtier, and are exposed to dirtier and dirtier water. this gives you the strongest ability to maintain a steep concentration gradient.

Manderx,

Would a co-current flow be superior to counter-current flow in filtering soluble proteins? In a co-current flow, the same protein remains in proximity to a bubble during the contact time. In counter-current flow, bubbles and proteins flow in opposite directions. A protein will not have the requisite 2 minutes of dwell time with the same bubble although it will have more opportunities to attach to different bubbles. While the counter-current skimmer will allow a greater concentration of proteins at the top of the gradient, the dwell time will not be there. Is contact time with the same bubble necessary or are opportunities for attachment to many bubbles sufficient?

There should be experimental data on this issue but I'm not sure how to find it. Has there been a "skim-off" between co-current skimmers (ATI, Bubble King) and counter-current skimmers (Deltecs, H&S)?

 

[BeanAnimal]

Would a co-current flow be superior to counter-current flow in filtering soluble proteins? In a co-current flow, the same protein remains in proximity to a bubble during the contact time. In counter-current flow, bubbles and proteins flow in opposite directions.

Your missing a key component. The counter current forces the bubbles to ruse slower. We keep talking about turbulance for a reason.

We are NOT talking about water passing bubbles, we are talking about water STUCK to the surface tension of bubbles. The longer the bubbles stay in the system, the better chance they have of pulling the protein from the water bound to the surface tension.

Counter Current creates an environment where bubbles do not rise as fast. Co-current will cause them to rise faster.

Turbulance knocks water/protiens away from the surface tension of the bubbles and the process has to start over again.

 

[hahnmeister]

Well... turbulence is a two-way street. Holmes-Farley points out that a certain level of turbulence is needed... not enough and bubbles dont have their boundary layer put into contact enough to gather proteins... er rather, interface. Too much, and this boundary layer loses the proteins it has gathered. So there is a 'sweet spot' for turbulence. There is also an ideal concentration of bubble volume to water volume... in the past I have heard 13% mentioned... not sure about this myself actually, I use other calculations, like lph/sqaure inch of diameter.

The turbulence thing is what makes me wonder about the possible merits of these cone shape skimmers... could the abrupt transition that many skimmers have in the neck where bubbles rise up and hit a near horizontal 'wall' cause them to lose their 'passengers'? This would mean that there would be a 'drop-off' of proteins near the top of the skimmer though still, and that another bubble could still pick up the proteins here (unless turbulence here was too high and the proteins could get spun back down). But it would suggest that the only proteins that actually make it through would be the ones that rise up into the neck in a straight shot w/o hitting part of the reducing funnel.

 

[BeanAnimal]

"Sweet spot for turbulance" I had not read that, but certainly do not doubt that it is true.

Escobal mentiones the 13% air to water. We had a pretty in depth look at the numbers and they appear to be pretty close. It is hard to get above 13%, when you do there isnot enough water and you have fairly dry foam that does not rise. We (mostly TinyGiants... he gets the credit) worked on a spreadsheet to do the calculations.

As for the neck and turbulance, it think it is skimmer dependent and involves many factors. Some do a better job than others in that depertment. Tuning also plays a large role I would assume.

 

[pjf]

When Escobal observed that some proteins require 2 minutes of contact time to bind to a bubble, was he observing a co-current flow or a counter-current flow?

 

[sherm71tank]

Which proteins need two minutes?

 

[pjf]

<a href=showthread.php?s=&postid=10699583#post10699583 target=_blank>Originally posted</a> by sherm71tank
Which proteins need two minutes?

"It was estimated by Escobal that some proteins take upwards of 2 minutes contact time with air to attach properly." (http://www.hawkfish.org/snailman/skimmer101.htm)

I don't have Escobal's book (Aquatic Systems Engineering: Devices and How They Function) but I believe that proteins that are more soluble and harder to skim are those that would require greater contact time. Gelbstoff (yellowing compounds) is an example of proteins that are more soluble and hence harder to skim.

It would be instructive to know if Escobal meant 2 minutes of co-current contact time or 2 minutes of counter-current contact time.

 

[ralphie16]

DP

 

[ralphie16]

<a href=showthread.php?s=&postid=10671788#post10671788 target=_blank>Originally posted</a> by pjf
Thanks! I'd appreciate it if you can PM your address to me.

The yellowing compounds are called Gelbstoff.

LOL, i hope you realize thats just a word what those crazy Krauts use to describe the yellow water. its no scientific word describing compounds. it may SOUND scientific but trust me, its just another language.

 

[sherm71tank]

<a href=showthread.php?s=&postid=10699933#post10699933 target=_blank>Originally posted</a> by pjf
"It was estimated by Escobal that some proteins take upwards of 2 minutes contact time with air to attach properly." (http://www.hawkfish.org/snailman/skimmer101.htm)

I don't have Escobal's book (Aquatic Systems Engineering: Devices and How They Function) but I believe that proteins that are more soluble and harder to skim are those that would require greater contact time. Gelbstoff (yellowing compounds) is an example of proteins that are more soluble and hence harder to skim.

It would be instructive to know if Escobal meant 2 minutes of co-current contact time or 2 minutes of counter-current contact time.

Fine and well. If someone can tell me which proteins take two minutes to remove I would greatly appreciate it. Also, I don't think a greater counter current contact time would work on the " two minute protein" because the same water and air aren't traveling together.

 

[BeanAnimal]

<a href=showthread.php?s=&postid=10699933#post10699933 target=_blank>Originally posted</a> by pjf
"It was estimated by Escobal that some proteins take upwards of 2 minutes contact time with air to attach properly." (http://www.hawkfish.org/snailman/skimmer101.htm)

I don't have Escobal's book (Aquatic Systems Engineering: Devices and How They Function) but I believe that proteins that are more soluble and harder to skim are those that would require greater contact time. Gelbstoff (yellowing compounds) is an example of proteins that are more soluble and hence harder to skim.

It would be instructive to know if Escobal meant 2 minutes of co-current contact time or 2 minutes of counter-current contact time.

Your missing the key point. It is not "co-current" or "counter-current". It is CONTACT time. The type of "current" is what makes that contact time possible.