Comparative Organics Test for Skimmers
 

Most of the skimmer threads in the “Lighting, Filtration & Other Equipment” section suffer from anecdotal information and non-reproducible tests. Let me propose a comparative skimmer test and see if you think it is sound:

• Take a large sample of nutrient-laden water from a large aquarium. This may be water from a water change that is normally discarded. Measure its alkenol concentration with the Salifert Organics test kit. Optionally, you may dilute it with RO/DI water to a standard concentration.
• Divide the water into two separate tanks of equal volume, each with a small circulation pump.
• Place the two skimmers that you want to compare into the two separate tanks.
• Periodically (daily?) measure the alkenol concentration in the two tanks with the Salifert Organics test kit.
• The superior skimmer is the one that can produce the lower concentration of alkenols within the test period (a week?).

This test procedure is based on several assumptions, including:

1. The alkenol concentration measured by the Salifert Organics test kit is an indicator of DOC concentration.
2. A skimmer will reduce DOC’s to a certain concentration and then lose its skimming ability. A “superior” skimmer will reduce the DOC’s to a lower concentration than an “inferior” skimmer.

I believe that this procedure is superior to other procedures where:

• A Remora is taken to a cesspool to demonstrate that it can pull out more skim than a Bubble King at the Monterey Bay Aquarium.
• A wet skimmer demonstrates that it can drain a tank faster than a dry skimmer.

pjf


Another nice starting post :D

Craig Bingman did some assays on skimmate but never did do the article. If IIRC something like 90 % of the skimmate was plankton.

This topic actually germinated in the Salifert forum. Habib was asked what his Organics test measured and if it is an indicator of skimmer performance. His responses were cryptic:

[QUOTE][i]<a href=showthread.php?s=&postid=9405977#post9405977 target=_blank>Originally posted</a> by Habib [/i]
[B]It measures some types of enols like phenolic substances.


If your husbandry is not too bad then there is no use in using this test. [/B][/QUOTE]
[QUOTE][i]<a href=showthread.php?s=&postid=4168273#post4168273 target=_blank>Originally posted</a> by Habib [/i]
[B]There are some organics not easily removed by skimmers and also not degraded easily by bacteria.

The current test measures some of such organics.

We have got a newer version (much better) since quite a while now but was not fit to be marketed yet.

I expect to announce it being available somewhere next month and will also supply the details if scales and which organics the new one measures (which is a much broader range of organics compared to the current enol type of compunds). [/B][/QUOTE]

Nevertheless, if there is any positive correlation between the test measurements and levels of dissolved organic compounds (DOC), then the results are indicative of skimmer performance. While crude, it is less offensive to me than the anecdotal evidence presented on skimmer threads.

So 90% of skimmate is plankton, eh? Is plankton beneficial to corals as food or is it akin to bacterial blooms produced by carbon dosing that must be skimmed? I guess one coral’s meat is another’s poison.

Plankton food for corals :confused: Are you serious ? Of course, very big. Corals come out at night to feed on plankton. That is what they use their sting cells for, to capture and kill plankton. About 60 -90 % of their diet, depending on species, is from the byproducts of photosynthesis, hermatypic corals and the other remaining % is form feeding on plankton , organics and the likes of "marine snow" . Then there are the non-photosynthetic species, ahermatypic.

We still, IMHO, need some good assays on skimmate.

On a very low bio-load 55g+15g tank (just algea, a feather duster, two hermit crabs, and a zillion copepods), must of my skimate is a green fluid, which under microscopy is 'dead scum', with a heck of a lot of plankton and zooplankton.

As an experiment on this tank, last week I dumped about 1/4" of skimmate from my Seaclone 100 back into the tank, and have had a diatom/algea bloom that has completely opaqued my test tank. Macroalgea (both red hair and chaeto) have had massive die-backs, further feeding the opaqueing phytoplankton bloom. As of today, I'm turning my skimmer back on, and seeing how quickly it reduced the phytoplankton population.

As a side note, my feather duster is extremely happy during this test. Hermits not so much, but they get by, and the copepod population has boomed.

I think your assumption is that plankton would not be detected by the Salifert Organics test kit and therefore the test is not a good indicator of skimmer performance.

My view is that even if the Salifert Organics test kit cannot detect particulate matter, it will still have tremendous value if it can indicate dissolved organic compounds (DOC).

There is a market for filtration systems that can remove DOC's but leave plankton unharmed. Many skimmer makers advertise their systems as "plankton friendly."

[b]Many skimmer makers advertise their systems as "plankton friendly."[/b]

I only known of one the Tunze. Who are the others ?

The kit should be good for DOC only basically. Plankton is another beast as is POM.

"Plankton Friendly" Skimmers
 

[b]ETSS[/b] advertises its skimmers as “the most plankton friendly skimmer design available today” ([url]http://www.superskimmer.com/tank%20filtration%20guide.htm[/url]). “Its very plankton friendly "Downdraft"™ action will also be greatly appreciated by your tank's inhabitants” ([url]http://www.championlighting.com/product.php?productid=18266&cat=517&page=1[/url]).

[b]Poseidon[/b] skimmers, being a “Venturi type is more plankton friendly since, chopper skimmers tend tear up minute life that meets that impeller... It chopps water and creates bubbles nicely, but it also chopps up plankton/pods and other marine life which is vital for your tanks health” ([url]http://www.nautilusreef.com/html/poseidon_q___a.html[/url]).

“…[b]counter current[/b] skimmers are the most plankton friendly. Although some small plankton will be removed as particulate material, it is at least conceivable for plankton to survive the trip through the water pump and through the bubble column. Venturi skimmers are much harder on plankton, since significant pressure is applied to them as they pass through the venturi valve.Down draft skimmers are assumed to kill anything larger than single cell organisms that pass through them due to the force and mechanical stress the water is exposed to” ([url]http://www.seasky.org/aquarium/aquarium_faq_page02.html[/url]).

Ok but "I " don't' buy those claim, when compared to an old Tunze where they are much more plankton friendly than even a CC skimmer and work off of diffusion principals. Their skimmate is quite different than that of any other skimmer.

Take note that those statements contradict each other :)

"Its very plankton friendly "Downdraft" vs. "Down draft skimmers are assumed to kill anything larger than single cell organisms "

Tunze
[url]http://www.tunze.com/149.html?&L=1&C=US&user_tunzeprod_pi1[/url][predid]=-infoxunter027

kz's revolution has some bold claims as well..

"revolutionary skimmer series from Korallenzucht.de - patented cone Design and new, plankton-safe patented air supply. Very high performance and nevertheless absolutely noiseless with small power consumption. Available for all aquarium sizes starting from the end of February 2007. The newest state of the art, after our tests with absolutely best effectiveness for corals and water elements, without aggressive effects."

"The very natural and gentle skimming adds the air with a spacious nozzle which is very effective but nevertheless gentle. Thus the water is not chopped like by a needle wheel, so there are no elements precipitated and plankton is saved."

I'll have ot look at those. Thanks :)

Bold calims by Tunze, no ;) Tunze's have been around for over 2 decades and have proved themselves many times.

Results-Based Skimmer Testing
 

I agree that Tunze’s classic DOC skimmers with their centrifugal action have an excellent claim for being plankton friendly. This centrifugal action is explained in volume 3 of Delbeek & Sprung’s [u]The Reef Aquarium[/u]. A DOC test on the water column serviced by this skimmer may be a good indicator of its performance.

I believe that a DOC test can be valid for skimmers that are not “plankton friendly.” Particulate matter can often be easily removed by filter socks. One major expectation of a skimmer is that it removes dissolved organic compounds. This aspect of a skimmer’s performance can be indicated by a DOC test.

The advantage of a DOC test is that it can show the level to which the skimmer can lower the concentration of a particular kind of DOC. With further analysis, we can determine which type of DOC is best indicative of all dissolved organic compounds and develop a test for that specific type of DOC. Controlled periodic testing can show the rate at which the skimmer can lower the DOC levels.

This type of testing is based on the results in the aquarium’s water column. It does not depend on the amount or type of skimmate collected. One cannot place his skimmer in a cesspool and claim that his skimmer is superior based on the amount of skimmate collected. This type of testing does not care whether the skimmate is “wet” or “dry.” It may even be able to determine whether wet or dry skimming is superior based on the results in the aquarium.

I submit that results-based testing is as important as or even more important than trying to assay the contents of skimmate.

quick question:

What is an alkenol by definition?

Test of Ability to Remove Polar DOC's
 

Enols or alkenols are described in Wikipedia ([url]http://en.wikipedia.org/wiki/Enol[/url]) and are characterized in part by its hydroxyl group (-OH). Examples of alkenols are described at URL: [url]http://www.leffingwell.com/alkenol.htm[/url]. According to Habib, the CEO of Salifert, they are neither easily removed by skimmers nor easily degraded by bacteria ([url]http://archive.reefcentral.com/forums/showthread.php?s=&postid=4168273[/url]).

If enols are not easily removed by skimmers, it is probably because they are more soluble than many dissolved organic compounds due to its hydroxyl group (−OH) which renders it more electrically polarized. A DOC that is less soluble is more easily removed by a skimmer than a DOC that is more soluble.

If we measure skimmers by their ability to remove dissolved organic compounds, then it stands to reason that a superior skimmer will be able to remove more DOC’s that are in the soluble or polar end of the scale. Hence a reasonable skimmer test would be to determine its ability to remove enols that are more soluble and polar than many dissolved organic compounds in an aquarium.

pjf

I agree on your testing and think is does have godd merit ;)

E.J.

An alkenol is a Huge group of organics, where most give rise to a fragrance and flavor . They are formed when a alkene and a hydroxyl group is attached to one of the carbon atoms that make up the double C bond. Vitamin C has an alkenol within is structure so to speak. A better and more used term is Enols.

[url]http://caltechbook.library.caltech.edu/122/18/BPOCchapter17.pdf[/url]

[url]http://www.chemgapedia.de/vsengine/vlu/vsc/en/ch/12/oc/vlu_organik/keto_enol/racem_halo_haloform_alkylierung.vlu/Page/vsc/en/ch/12/oc/keto_enol/rea_enol/rea_enol.vscml.html[/url]

I am not big on these by a long shot :lol:

[b]Hence a reasonable skimmer test would be to determine its ability to remove enols that are more soluble and polar than many dissolved organic compounds in an aquarium.[/b]

Any just how do you plan to test for that ???

[b] they are neither easily removed by skimmers nor easily degraded by bacteria [/b]


Now how did you draw that from Habib, as he has no mention of it and you are fishing.

Thanks for the "reefer's" definitions. I have never heard of an alkenol!!!
As to enols .... definitely one of my favorite functional groups:D They are fairly reactive and I am suprised that they exist in aquaria in any significant amount....

Why not start the test with clean salt water and add a fixed quantity of a higher boiling point (BP) "alkenol". Then run the skimmers for a fixed time and extract the remaining "alkenol" from the saltwater and/or skimmate for quantification...

and how are you going to know it is still an alkenol/enol and what is going to happen to it in seawater ? Also did anyone look to see if alkenols / enols are hydrophobic or hydrophilic, since skimmers work off of hydrophobicity just like GAC.

The hydrophilicity of an enol will vary depending on what else is appended to it. Take an enol that caps a 20 carbon chain, and it will be greasy as hell, but an enol that caps a 2 carbon chain will be more hydrophilic. Regardless, the most polar enol in the world can easily be extracted from water with an organic solvent ... especially if tautomerized to the ketone ...

I am suggesting that we add an "alkenol" that is already known to be in saltwater. Thus we know it's stability in saltwater....


[QUOTE][i]<a href=showthread.php?s=&postid=10606854#post10606854 target=_blank>Originally posted</a> by Boomer [/i]
[B]and how are you going to know it is still an alkenol/enol and what is going to happen to it in seawater ? Also did anyone look to see if alkenols / enols are hydrophobic or hydrophilic, since skimmers work off of hydrophobicity just like GAC. [/B][/QUOTE]

From a chemical standpoint this conversation will be limited by the lack of identification of the compounds at hand. ...

Boomer, I have smelled some enols that would make you gag ..... twice

You said it is hydrophilic and skimmers work off of hydrophobic principals mostly. So they will not be extracted very well by skimmers. Or did you miss that ??

Hydrophobic surfaces attract hydrophobic substances and hydrophilic surfaces attract hydrophilic substances. The reason behind Polybiomarine Polyfilters, they are more hydrophilic and used to sup GAC and skimmers which are both mostly hydrophobic. Skimmers are not so good at removing hydrophilic substances.

What is Skimming?
[url]http://reefkeeping.com/issues/2006-08/rhf/index.php[/url]

lol .... we speak different languages

Enols are polar functional groups, which can be part of hydrophobic molecules. Without knowing the identity of the molecules at hand, none of us can make any reasonable guess as to it's affinity for hydrophobic surfaces. Furthermore, hydrophilicity is a continuum .... there aren't many either or cases...

I was thinking more along the lines of designning tests for evaluating skimmers for their ability to remove organics from saltwater: I though the experiments would be simplified by the controlled addition of organics to clean saltwater .... This would be a more rigorous set of experiments, as we won't know the composition of the DOCs in the "old" saltwater....

[QUOTE][i]<a href=showthread.php?s=&postid=10607091#post10607091 target=_blank>Originally posted</a> by Boomer [/i]
[B]You said it is hydrophilic and skimmers work off of hydrophobic principals mostly. So they will not be extracted very well by skimmers. Or did you miss that ??

Hydrophobic surfaces attract hydrophobic substances and hydrophilic surfaces attract hydrophilic substances. The reason behind Polybiomarine Polyfilters, they are more hydrophilic and used to sup GAC and skimmers which are both mostly hydrophobic. Skimmers are not so good at removing hydrophilic substances.

What is Skimming?
[url]http://reefkeeping.com/issues/2006-08/rhf/index.php[/url] [/B][/QUOTE]

No not different languages :lol:

[b]Enols are polar functional groups, which can be part of hydrophobic molecules. [/b]

Agree

[b]Without knowing the identity of the molecules at hand, none of us can make any reasonable guess as to it's affinity for hydrophobic surfaces. [/b]

Agree

[b] Furthermore, hydrophilicity is a continuum .... there aren't many either or cases...[/b]

So is hydrophobicity. So, most molecules are not all or either of them . Although there are extremes in both cases.

[b]I was thinking more along the lines of designning tests for evaluating skimmers for their ability to remove organics from saltwater[/b][

I agree and enols are only one groupe of many groups.

[b] I though the experiments would be simplified by the controlled addition of organics to clean saltwater[/b

Agree but we need to be looking at organics that are common to a seawater reef tank to be more in compliance.

Habib Redux
 

I plan to test for enols with the Salifert Organics Test. Let me quote Habib for the second time in the same thread:
[QUOTE][i]<a href=showthread.php?s=&postid=9405977#post9405977 target=_blank>Originally posted</a> by Habib [/i]
[B]It measures some types of enols like phenolic substances.


If your husbandry is not too bad then there is no use in using this test. [/B][/QUOTE]
- [url]http://archive.reefcentral.com/forums/showthread.php?s=&postid=9405977[/url] (3/06/2007)
[QUOTE][i]<a href=showthread.php?s=&postid=4168273#post4168273 target=_blank>Originally posted</a> by Habib [/i]
[B]There are some organics not easily removed by skimmers and also not degraded easily by bacteria.

The current test measures some of such organics.

We have got a newer version (much better) since quite a while now but was not fit to be marketed yet.

I expect to announce it being available somewhere next month and will also supply the details if scales and which organics the new one measures (which is a much broader range of organics compared to the current enol type of compunds). [/B][/QUOTE]
- [url]http://archive.reefcentral.com/forums/showthread.php?s=&postid=4168273[/url] (1/24/2005)

[QUOTE][i]<a href=showthread.php?s=&postid=10607229#post10607229 target=_blank>Originally posted</a> by Boomer [/i]
[B]

[b] I though the experiments would be simplified by the controlled addition of organics to clean saltwater[/b

Agree but we need to be looking at organics that are common to a seawater reef tank to be more in compliance. [/B][/QUOTE]

Unfortunately, I don't know much about reef chemistry ... what are the organics that are common to seawater?