New Skimmer – Price is no Object!

[hahnmeister]

Wouldnt have to petition... our club has a resident Dr. in chemistry, doing enzyme research actually. As for spectrometer testing, my spectrometer just touches the 300nm range.

Anyways, to get back to the original 'challenge' for a skimmer that could actually make the water clearer... lower turbulence and a longer dwell time seem to make a huge improvement... I grabbed a review of the ATB vs. the ATI and posted it here:
http://reefcentral.com/forums/showthread.php?s=&postid=10704231#post10704231

Notice the nutrient levels as well as the water clarity improvements noted. Thought some of you might be interested. Keep in mind that the air throughput in both skimmers should be about the same, or if anything, the 'threadwheel skimmer' would have slightly more air intake.

 

[BeanAnimal]

The question of testing still comes down to cost vs benefit and the fact that one test is not going to tell you much

 

[pjf]

No Gelbstoff in Germany?

No Gelbstoff in Germany?

<a href=showthread.php?s=&postid=10701349#post10701349 target=_blank>Originally posted</a> by Klaus Jansen
Hi Ralphie..
nobody use the name : .. Gelbstoff... in Germany... the Krauts are using best skimmers and make many waterchange... Nobody in Germany now Gelbstoff...

regards. Klaus

Klaus,

It seems that in Germany, Gelbstoff is no longer a problem. Is that due to better skimmers or due to more water changes?

Thanks!

 

[pjf]

One Test Suffices & Already Developed!

One Test Suffices & Already Developed!

Suppose someone developed a test for Gelbstoff, such as a color card. If a skimmer can skim Gelbstoff, then the same skimmer can skim all organics that are less soluble, such as surface proteins. Therefore, one test can tell us a lot!

The same applies for other organics. If a DOC of solubility K can be skimmed, then the same skimmer will be able to more readily skim DOCs of solubility j < K. It is unlikely that you will find skimmers A and B such that A will skim organic X better and B will skim organic Y better. Both skimmers will skim the less soluble protein better.

The test does not need to measure only one DOC. In comparative testing (2 skimmers, 2 tanks, same water), it may work even if it tests for a class of DOCs. The test only needs to indicate which skimmer can reduce the concentration of the tested organics more.

To better differentiate the "men from the boys," the test should measure moderately hard-to-skim organics that are more soluble than surface proteins, but not as soluble as Gelbstoff that few, if any, skimmers can remove.

The Salifert Organics Test is designed to test for DOCs known as phenols. It may not have the requisite resolution now but it is a good starting point. Today, it is adequate for comparisons between Remoras and Bubble Kings. Tomorrow, it may be improved to test other skimmers.

The Gelbstoff test is ready now and waiting for a skimmer to test!

 

[aninjaatemyshoe]

"The question of testing still comes down to cost vs benefit and the fact that one test is not going to tell you much"

First of all, I wouldn't have the illusion that this test would be developed or used by any skimmer developer/manufacturer. If there is a test developed, it would be from purely hobbiest interest. I'm not really arguing for testing, but couldn't the argument of cost vs. benefit be pitted against our entire hobby? To many, the expense we pay to upkeep our aquariums would seem ludicrous already.

 

[BeanAnimal]

Suppose someone developed a test for Gelbstoff, such as a color card. If a skimmer can skim Gelbstoff, then the same skimmer can skim all organics that are less soluble, such as surface proteins. Therefore, one test can tell us a lot!

What makes you think that? Several of you just got through talking about the complexity of the air/water interface and how it may not JUST be contact time, but a much more complex physical and chemical interaction. It would follow that the differnece is not as simple as "more or less soluble."

You can't have it both ways. You have proposed an idea (and not a bad one), but applied it as science based on assumption.

The devil is in the details.

 

[pjf]

Re: One Test Suffices & Already Developed!

Re: One Test Suffices & Already Developed!

<a href=showthread.php?s=&postid=10704831#post10704831 target=_blank>Originally posted</a> by pjf
If a DOC of solubility K can be skimmed, then the same skimmer will be able to more readily skim DOCs of solubility j < K. It is unlikely that you will find skimmers A and B such that A will skim organic X better and B will skim organic Y better. Both skimmers will skim the less soluble protein better.

When it comes to skimmers, it does come down to what is more or less soluble. Here's Randy's discussion of skimming principles: http://reefkeeping.com/issues/2006-08/rhf/index.php. The reason for discussing contact and dwell time is to determine how to best skim the more soluble DOCs. When we pondered the "2 minutes" of contact time, it was to bind these DOCs, such as Gelbstoff or Gilvin, which are more polar and hydrophilic.

If there are dissenting assumptions, it would be nice to see your scientific references.

 

[hahnmeister]

So, what the cichlid breeders did back in the day might be the easiest still... make a yellow-scale card to go behind the tank... as the tank gets more and more yellow, the darker and darker shades/bands of yellow will vanish. Its a purely subjective test though... as everyone would have a different card of yellows, and everyone's tanks would most likely have different lighting and thickness... but as a subjective comparative test, it would be informative enough for side by side comparisons.

 

[Fishbulb2]

<a href=showthread.php?s=&postid=10706268#post10706268 target=_blank>Originally posted</a> by hahnmeister
So, what the cichlid breeders did back in the day might be the easiest still... make a yellow-scale card to go behind the tank... as the tank gets more and more yellow, the darker and darker shades/bands of yellow will vanish. Its a purely subjective test though... as everyone would have a different card of yellows, and everyone's tanks would most likely have different lighting and thickness... but as a subjective comparative test, it would be informative enough for side by side comparisons.

I like this method. What I would propose is that to "test" a skimmer you mix up a 50g bag of Instant Ocean in some form of container. Then add a given amount of phenol dye, like the Gelbstoff or something. This should raise this water by a fixed amount on hahn's yellow-scale card. Now you place any given skimmer in this tub and let it skim for a fixed amount. Then you determine how many shades it has dropped on the card. You are right hahn that it will depend also on how the card is viewed so you could use a test kit vial to minimize tank thickness issues ect.
This test would make the assumption that a skimmers relative performance can be based by comparing their ability to skim out this one substance. Personally, I believe that to be true. Any skimmer that is more effective at removing this compound will also be more effective at removing higher or lower solubility proteins than a skimmer which performs worse on this test. The biggest hurdle would be convincing people to mix up 50g of IO doing all of this just to test a skimmer. Also standardizing the color chart might be tough. Oh well, it's a nice thought.

 

[hahnmeister]

<a href=showthread.php?s=&postid=10704738#post10704738 target=_blank>Originally posted</a> by BeanAnimal
The question of testing still comes down to cost vs benefit and the fact that one test is not going to tell you much

Well, this test in particular compared two rather similar skimmers with respect to overall height and air intake. The difference was in the body shape, but also in the distance/turbulence from the bottom to the top of the skimmer. If anything, the ATB has a slightly lower air intake on 220v (needlewheel eheims on 220v/50hz often max out at 750-some lph of air). Anyways, the comparison, although not side by side, was rather controlled. It was on a well established tank, and with no other variables being changed. IF anything, the tester showed lower nutrient levels while being able to reduce his vodka dosing as well as remove his phosphate reactor. Thats what got me in the end. Being able to remove/reduce two other forms of filtration as a consequence and maintain lower levels... cant argue with that.

I thought that the methodology was more in line with what we might consider practical, since the tester in this case also agrees that comparing amounts of skimmate is usually not a fair way to go about comparing.

 

[BeanAnimal]

Re: Re: One Test Suffices & Already Developed!

Re: Re: One Test Suffices & Already Developed!

<a href=showthread.php?s=&postid=10706090#post10706090 target=_blank>Originally posted</a> by pjf
When it comes to skimmers, it does come down to what is more or less soluble. Here's Randy's discussion of skimming principles: http://reefkeeping.com/issues/2006-08/rhf/index.php. The reason for discussing contact and dwell time is to determine how to best skim the more soluble DOCs. When we pondered the "2 minutes" of contact time, it was to bind these DOCs, such as Gelbstoff or Gilvin, which are more polar and hydrophilic.

If there are dissenting assumptions, it would be nice to see your scientific references.

IMHO You are still missing the big picture.

Lets make this much simpler so that everybody else following along can possibly understand. We don't need any science or silly terms.

You have a skimmer that has 10 bubbles per hour rising through it. Those bubbles have a certain propensity to attract certain things. Lets call those 'things' A, B, C and D.

Let us also assume that we can very the "dwell time" or whatever variable controls the type of things that the skimmer is able to handle. I.E. what they have a propensity to attract. For THAT IS exactly what we are talking about.

A = the least soluble (what you keep calling surface proteins)
B= is a little more soluble
C= is more soluble and what you call "Gelbstoff" (what an annoying word). and yellow
D = is the hardcore yellow stuff


Now lets give these things an arbitrary concentration.

A=25
B=25
C=25
D=25

Lets also say that you have a skimmer that is capable of removing A, B, C, and D.

If we have a finite interface (10 bubbles per hour in this example) then we have a finite number of items that can be removed in a given time.

If we measure the D that is left in the tank, we still have to account for the A, B and C, or we have no idea how well the skimmer does overall. Remember it is removing more than just D.

Lets say:

Skimmer one removes:
10 A
20 B
10 C
10 D
That is 50 items in 5 hours.


Skimmer two removes:
20 A
20 B
5 C
5 D
That is 50 items in 5 hours

Skimmer three removes:
5A
5B
5C
35D
That is 50 items in 5 hours.

Which skimmer is better? We can make it even more complicated by changing the volume of skimmate over time X.

If ONLY D is our concern then the test would be valid, D is NOT our only concern (as your first post stated, you want a skimmer that does it all!).

Testing for D would say that skimmer 3 is better. It removes more yellowing compounds. BUT it leaves the less soluble stuff behind. What about skimmer 1? It does an overall good job. And skimmer 2?

Thus, Randy, Habib et al. refrain from describing how we determine what the best skimmer is. It is all a matter of perspective. Remember the "moving target" and similar remarks made by those that have been cited?

In the real world we have more than 10 bubbles per hour, but we still have a finite limit and a large range of proteins to choose from. Please don't let the simplicity of the example become a straw argument. It is fully scalable.

Lets put this in another very simple context:
It is a work/time problem. We can only do a finite amount of work in a finite amount of time, yet the work involves complicated interactive tasks. Changing one portion of 1 task changes the overall amount of the other types of work that get done.

Each skimmer (or skimmer setting for that matter) will produce a different outcome. What exactly do you measure to rank performance?

I will say it again, there are just too many variables to consider for any reasonable (cheap and easy) test to be of ANY real use.

Though this conversation is enlightening and has produced some great responses and counters. However, it is merely a lot of serious tilting at windmills.

 

[pjf]

Deeper is Better

Deeper is Better

All bubbles have a propensity to attract hydrophobic compounds and repel hydrophilic compounds. You will not find different bubbles such that one is more attracted to surface proteins and another is more attracted to yellowing compounds. All bubbles will be more attracted to surface proteins than “Gelbstoff” or “Gilvin” or chromophoric dissolved organic matter (CDOM). All bubbles will repel hydrophilic or polar molecules.

Let’s take your 4 compounds (A, B, C, D), of equal concentration but different solubility such that on the solubility scale, less of A will dissolve in aquarium water than D (A < B < C < D).

• Compound A will quickly bind to a bubble and be removed by the skimmer.

“Nearly any hydrophobic or amphipathic molecule can be skimmed out to some extent. This list includes amino acids, vitamins, proteins, carbohydrates, fats, many combination biomolecules (e.g., lipoproteins, liposaccharides), RNA, DNA, etc. This list includes most, but certainly not all, organics. Fortunately, it includes many of the organic compounds that lead to yellowing in marine and reef aquaria, so skimming can help reduce the yellowing of aquarium water.” - Randy Holmes-Farley (http://reefkeeping.com/issues/2006-08/rhf/index.php)

• Compound B may bind to a bubble only to be replaced by compound A as the bubble rises.

“Additionally, different organics have different binding strengths to the air/water interface. Compounds which bind more strongly will slowly replace those already at the interface which have weaker binding. Thus, a bubble which is completely occupied with organics might still be changing with time upon further exposure to aquarium water.” - Randy Holmes-Farley (http://reefkeeping.com/issues/2006-08/rhf/index.php)

• Compound C may take two minutes of contact time to bind to a bubble.

“Some organics require up to 2 full minutes of contact time with air bubbles in a skimmer before they are removed via foam fractioning.” â€"œ (http://www.hawkfish.org/snailman/skimmer101.htm)

• Compound D may never bind to a bubble

“Most highly polar organics will not be removed by skimming. Simple sugars, acetate, oxalate, methyl alcohol, choline, citrate, etc. will remain behind. They simply are not sufficiently attracted to an air water interface. Most charged species are, in fact, repelled from the air/water interface, so they are not collected. Fortunately, many of these highly polar organic materials are readily metabolized by bacteria and other organisms, so they do not continually build up in marine aquaria.” - Randy Holmes-Farley (http://reefkeeping.com/issues/2006-08/rhf/index.php)

Conclusions:
1. All skimmers will remove compound A better than compound B, B better than C, and C better than D.
2. Skimming “deeper is better:”
• If a skimmer can remove B, it will also remove A.
• If a skimmer can remove C, it will also remove A & B.
• If a skimmer can remove D, it will also remove A, B & C.
3. “Shallow skimming is worse:”
• If a skimmer can’t remove C, it can’t remove D.
• If a skimmer can’t remove B, it can’t remove C & D.
• If a skimmer can’t remove A, it can’t remove B, C & D.

If Randy is right, we may not need a test kit to measure CDOM (C & D). Maybe a color card is all we need.

Bottom Line:

Popular skimmer designs are based on rapid removal of surface proteins with large air to water ratios in order to impress uninformed aquarists with the amount of foam generated and the amount of skimmate collected. Their tanks still look yellow with chromophoric dissolved organic matter (CDOM) and require ozone, carbon or water changes to be presentable.

“A fool and his money are soon parted.”

 

[Fishbulb2]

Re: Deeper is Better

Re: Deeper is Better

<a href=showthread.php?s=&postid=10707929#post10707929 target=_blank>Originally posted</a> by pjf

Conclusions:
1. All skimmers will remove compound A better than compound B, B better than C, and C better than D.
2. Skimming “deeper is better:”
• If a skimmer can remove B, it will also remove A.
• If a skimmer can remove C, it will also remove A & B.
• If a skimmer can remove D, it will also remove A, B & C.
3. “Shallow skimming is worse:”
• If a skimmer can’t remove C, it can’t remove D.
• If a skimmer can’t remove B, it can’t remove C & D.
• If a skimmer can’t remove A, it can’t remove B, C & D.

This is exactly what I wanted to post last night (don't know why i couldn't get on RC). I don't see how this can not be true. It's what i've been trying to say all along as well. A bad skimmer may only remove compound A, but a great skimmer will also have to remove compound A before moving onto more soluble compounds like B,C, and D. I cannot see how a skimmer can remove more of D than A? So as long as you are comparing skimmers against the same compound, in the same concentration, you should have a really good idea of their relative performance. The disadvantage of choosing a compound like D is that most low end skimmers won't even show up on the radar. But B or C may very easily show the whole range of skimmer performance. Of course, finding the appropriate compound at the right concentration to cover a large range of skimmer performances would be difficult. That's really the only devil in the details that I see. Otherwise, I think everyone else is making this too complicated.
FB

 

[gcarroll]

The way I see it is just because a skimmer is capable of removing C & D, does not mean it will ever remove C & D. If the skimmer is not efficient enough at removing A & B it will never have the opportunity to remove C & D. Even if it has the recommended 2+ minute dwell time. This may mean that the best skimmer performance may be measured by the skimmer that removes the most A & B.

 

[BeanAnimal]

PJF, you are making a lot of assumptions to come to your conclusion. You have actually just reinforced my point. Your conclusions are fine as a postulate, but nothing more.

Just because it can remove A, B, C and D does not mean that it will do so at a predictable rate, and that is exactly what you are basing your entire premise on.

Try this please:
1. All skimmer can remove compound A better than compound B, B better than C and C better than D. But will do so at different ratios depending in operating parameters.
2. We are not sure if deeper skimming is better. Furthermore:
• If a skimmer can remove B it MAY also remove A
• If a skimmer can remove C it MAY also remove A & B
• If a skimmer can remove D it MAY also remove A, B & C
3. There is no inverse logic here, as the point is redundant.

The skimmer may remove A and C better than B and D, even though it is capable of removing all four. So you can NOT just measure the "color" of the water to determine how well the skimmer performs. You are just measuring the color of the water.

There is a finite amount of compound that is removed over a given time.

HERE IS THE KEY POINT:
If we follow your proposed logic, and the skimmer was able to remove A, B, C, and D...

And it did so according to your explanation of binding...

Then the D component would have to be fully removed from the system before the skimmer removed ANY C. Etc.

So your logic equates to:

IF and ONLY IF D where non existent or skimmed out, would the skimmer remove any C

IF and ONLY IF C and D where non existent or skimmed out, would the skimmer remove any B

IF and ONLY IF A, B and C were non existent would the skimmer remove A.

You can't have the logic both ways. The wonderful thing about logic is that a simple table can be used to show the possible outcomes.

So you say "that is not what I said!". Well then we MUST conclude that a skimmer does not pull the compounds out in the manner that you have proposed.

Instead, it pulls out compounds in a mixed fashion according the the settings and type of skimmer. The ratio of the compounds removed can vary vastly, even if a skimmer IS capable of removing ALL types. Therefore, you CAN NOT measure the extraction of ONE compound and draw a conclusion about the other compounds that have been removed.

Your logic would also dictate that for a D to be bound it MUST take the place of a C, but the C MUST have taken the place of a B and the B the place of an A.

You say "that is not what I said:. Well then we MUST conclude that a skimmer can bind a D without replacing another compound in the process. That therefore means that the resulting extraction ratio of A : B : C : D is NOT fixed and therefore testing for ANY single compound tells you NOTHING about the concentration of the other compounds. It also does not indicate the overal performance of the skimmer. It just shows that the performance as it relates to what you tested for

If your ONLY CONCERN is that ONE COMPOUND, then you measure for it and select or tweak a skimmer try and maximize the amount of that compound that is removed. You have stated the exact opposite, you want a skimmer that does it all and a test that confirms the efficiency at which it does it all.

It is not going to happen my friend, at least not with a yellow card and a few bucks.

 

[hahnmeister]

My impression of Gelbstoff from all the articles is that it is not something that is directly removable by itself, but rather that it is what happens with whatever the skimmer isnt able to remove, no matter if it is protein 'A', 'B', or 'C'. Its a byproduct of the aerobic bacteria dealing with waste... by skimming out as much as possible before it gets to the nitrogen cycle, thats how to minimize the yellow. But other than carbon, I dont think there is a way to remove this tint from the water through skimming, only to prevent it. And since a skimmer wont get 100% out anyways... just the hydrophobic, there will always be some sort of tinting in the water. I think thats why you need to run carbon and do water changes no matter what. Also, it makes a strong case for vodka/sugar... as in carbon dosing. The bacteria produced through dosing wil consume the less or non hydrophobic proteins/DOC's, and then you can harvest the bacteria through the skimmer. Vodka dosing is a way to enable your skimmer to grab more of whats in the water in the first place.

 

[Fishbulb2]

<a href=showthread.php?s=&postid=10708695#post10708695 target=_blank>Originally posted</a> by BeanAnimal

So your logic equates to:

IF and ONLY IF D where non existent or skimmed out, would the skimmer remove any C

IF and ONLY IF C and D where non existent or skimmed out, would the skimmer remove any B

IF and ONLY IF A, B and C were non existent would the skimmer remove A.

No i think this is backwards from what we are saying. I think we are saying that

IF and ONLY IF C where non existent or skimmed out, would the skimmer remove any D

IF and ONLY IF C and B where non existent or skimmed out, would the skimmer remove any D

IF and ONLY IF A, B and C were non existent would the skimmer remove D.

You must skim out more soluble proteins (A,B,C) before you can pull out insoluble ones like D. I don't think you can ever get the sceneros you previously posted were one skimmer was pulling out 4 times as much D as A. If A is more insoluble, then you MUST pull out a before D now matter how you set up the skimmer or A will simply dislodge D. I really has to work that way.
FB

 

[hahnmeister]

Which version do you believe?... that a skimmer can just be better at A, B, or C, or that if A, then also B, then also C, but C does not mean B, and B does not mean A... (you get what I mean, not being technical here). I think thats where the two sides clash in the end. Holmes-Farley's model suggests that a skimmer may spend all its time being better at B, but that it doesnt mean that it will also cover all of A or C. his model suggests that as a bubble dwell's longer, the less attracted DOC's will be replaced by the more attracted... so a lesser attracted substance could be 'bumped' off. I suppose these would be considered more 'stubborn' substances according to Escobal... but it suggests that a longer dwell time could work against you. OTOH, it is a strong case for recirculating skimmers. If the throughput is too high, the lesser attracted DOC's could get blown out the outlet before there is a 'spare' air bubble to latch on to. With a recirculating (taller), you can slow the process down some... the water will in effect be passing through more air, as would it be if the skimmer was shorter and wider, and just used 2x as much air. But the problem seems to be that after a while, assuming your skimmer overtakes the production of waste in the tank, there isnt enough in the water to produce a stable foam head. A recirc might waste bubbles as well, but having the smaller diameter neck (since it doesnt have to have the extra neck space just in case the DOC level is high and it needs it for every bubble to collect w/o overflowing the cup) the skimmer is still able to function while the DOC levels are lower... which unless your skimmer is undersized, will happen at some point (assuming equilibrium is not stable/possible, which I would assume is the case).

 

[BeanAnimal]

Fishbulb, that is not what PJF said

But lets take what you say at face logic value:

A MUST be ELIMINATED before B can be bound.
B MUST be ELIMINATED before C can be bound.
C MUST be ELIMINATED before D can be bound.

Furthermore if a single D is removed, then NO A, B, or C would be left.
Again, you can't just short circuit the logic to fit the arguement or conclusion.

So if the above IS true, then given (2) skimmers that can remove D, the skimmer that has more throughput will be the better skimmer.

Now here is the kicker: (if we use the logic your proposed)

Given 2 skimmer that CAN remove D:
The skimmer that fill the collection cup the fastest will be the more efficient!

You can not have the logic both ways!

I can hear the moans! We all know that what I have just said is far from the truth.

So that MUST mean that a given skimmers collection cup can AND IS a mixture of A, B, C, and D. The ration depends on the skimmer and the settings. Measuring the amount of D removed is not meaningful

Again, back to the fact that a fixed amount of material is removed in a fixed amount of time, and that ratio is not fixed. Lets us beg the question yet again. WHAT IS THE DEFINITON OF A GOOD SKIMMER? WHAT COMPOUNDS should be be more concerned about A, B, C, or D and what ratios are they found in our tanks? What ratio is best to keep or target? Ahhh qestions that have no easy answers.

Shall we tilt at a few more windmills... I kind of have fun doing it

 

[pjf]

Algal Source for Gelbstoff & Gilvin

Algal Source for Gelbstoff & Gilvin

Hahn,

According to this definition of Gelbstoff and Gilvin, chromophoric dissolved organic matter (CDOM) can also come from macroalgae that secretes phenolic compounds.

"Dissolved material in sea water that is resistant to bacterial attack. Its name comes from the yellow color it imparts to the water. Brown algae, the principal algae group growing in coastal waters of temperature and higher latitudes, excrete phenolic compounds. These polyphenols are converted into a brown polymer by secondary reactions with carbohydrates and proteins of algal origin. The properties of the resulting substance are identical with Gelbstoff. Its concentration in sea water is around 1 mg/l and it is removed mainly by precipitation since its phenolic nature renders it resistant to bacterial attack. This is also known as yellow substance or gilvin. See Riley and Chester (1971)."
(http://oceanography.expert-answers.net/glossary-word/en/Gelbstoff.html)

gcarroll,

You are correct. Since surface proteins (A & B) can replace more soluble organics (C & D) as the bubbles rise through the gradient, a skimmer must reduce the less soluble compounds (A & B) first to give other organics a chance to be removed. My view is that many skimmers don't have the contact time to skim beyond surface proteins. In other words, many skimmers can only "skim the top" because of high turbulence or short contact times.

Fishbulb2,

I'm sure that Randy Holmes-Farley agrees with you 100%. The order of skimming is based on hydrophobicity. If a skimmer can skim the more soluble organics, it can skim the less soluble organics.

BeanAnimal,

If you can cite scientific references to support your views, that would be appreciated.

Thanks!