Comparative Organics Test for Skimmers

[Habib]

Originally posted by pjf
Thanks, E.J.
I've considered buying a "pre-owned" UV spectrophotometer to look at protein absorption characteristics.

Hopefully, a simpler test can be found or developed. Skimming is based on the solubility of the protein. If a protein has solubility, K, then all proteins of solubility, j < K, should be more readily skimmed and all proteins of solubility, l > K, should be less readily skimmed.

Hence, a single indicator test should work. Habib's Organics Test is a good start.

What about those that do adhere on particles or form precipitates?

How about proteins that decrease in size due to bacterial action and are less likely to be skimmed. It would be very tricky to think it would happen in the same extent regardless which skimmer is used.


Just a few thoughts.


There a are a few threads regarding organics in water and one also has some info the use of UV spectroscopy.

[Boomer]

So in short, you are saying that kit would not be a good indicator I kinda figured it would be poor or very crude means and may be misleading. ORP, I would not think or buy in a heart beat as good indicator. It is way to complicated a measurement with to many potential variables to shift its readings

[PatrickJ]

what about water turbidity?

[pjf]

Here's a comparative test that may work:

1. Fill two 10-gallon tanks with water discarded from a marine aquarium water change.
2. Place a skimmer on each tank.
3. Measure the Gelbstoff with a color card daily. The tank with the least yellowing compounds has the winning skimmer.
4. If you can't differentiate the color, use the Salifert Organics test or a spectrophotometer.

You can test for any DOC that is moderately hard to skim (not easy-to-reach surface scum). If a skimmer can reduce the concentration of that DOC, it will certainly reduce the concentration of all DOCs that are less soluble.

[pjf]

Originally posted by PatrickJ
what about water turbidity?

Does water turbidity correlate with the concentration of dissolved organic compounds?

In other words, if DOC levels increase then does turbidity increase?

[sirrus6]

All

I have been following this thread with some interest, as in fact I have been testing skimmer performance with the aid of some enthusiastic aquarist/students at Penn State University. (see http://archive.reefcentral.com/forum...readid=1035462).

Specifically, we have purchased one member of each class of skimmer:

needlewheel: EuroReef CS80

venturi: Precision Marine ES 100

downdraft: ETSS evolution 500

airstone: Precision Marine AP 624 (we had them custom-make this skimmer for us)

We then measure the kinetics of bovine serum albumin (BSA, a test case protein available for cheap in large quatities; starting at 10 ppm) depletion in a 35 gal saltwater aquarium under standardized conditions (i.e., volume, flow, temp, etc) using a Pierce microprotein assay kit and Beckman DU70 spectrophotometer.

We have adequately tested the CS80, ES100, and ETSS 500, but only about half the runs on the AP624 are completed. I am currently looking for a new student co-worker to complete these studies, and to perhaps expand to other organics as models for DOC components - for example, the Pierce kit, which is really an oxidation measuring assay, will detect glucose (as a model carbohydrate) down to the ~ 1 ppm level.

I hope to have this preliminary study wrapped up this year (if I can hire the student), and to submit the results to ReefKeeping for publication. We definitely do see differences between the different skimmers in terms of the rate at which they remove BSA from saltwater. I would prefer not to discuss the results in this forum at present, because of the inevitable controversy surrounding the decision to use a model system (i.e., BSA) to represent an unknown (aquarium "protein", or more generally "DOC"). That is, I think that acceptance of any data on a controversial topic such as skimmer performance will require a lot of preliminary explanation and context, best developed within a comprehensive article.

Cheers

Ken

[Boomer]

Great Ken can hardly wait I hope you are keeping Sanjay on his toes

[Boomer]

In other words, if DOC levels increase then does turbidity increase?

It may or may not it depends on the DOC's.

3. Measure the Gelbstoff with a color card daily. The tank with the least yellowing compounds has the winning skimmer.
4. If you can't differentiate the color, use the Salifert Organics test or a spectrophotometer.

There are other test kits, I just forgot about them. Getting to old Some how Ken reminded me of them.


The are called "Color" tests. LaMotte makes two of them, CT-PC and CW-HR. The first is a dual range drop pipet and the latter is a octet comparator with a axial reader. They use platinum cobalt color stds. HACH also make one CO-1. These kits are for apparent color created by dissolved substances. There are also other kits that may work, like the one I sent to Randy. The LaMotte Tannin/Lignin, TL kit or their Phenol kit P-52-R. And the HACH Tannin/Lignin, TA-3 and the Phenol kit PL-1. How well these will work in seawater I don't know.

[pjf]

Ken,

Thanks for undertaking the task of testing protein skimmers. My advice is to use as an indicator the most soluble organic compound that is both easily measured and capable of being skimmed. The theory is that if a skimmer can skim this compound, it can readily skim all compounds of lesser solubility.

I hope that your results can be released sooner rather than later. I am shopping for a skimmer that can skim chromophoric dissolved organic matter (CDOM) without ozone or carbon filtration but it looks like I will have to await your results before making a selection.

If I live near Penn State, I would volunteer to assist you. Good luck and best wishes on your research!

[PatrickJ]

Originally posted by pjf
Does water turbidity correlate with the concentration of dissolved organic compounds?

In other words, if DOC levels increase then does turbidity increase?

I believe so, because the yellowing compounds do decrease light transfer, so yes it would add to turbidity.

Would be intresting to test.