DEBATE: Skimmers Yes or No

[Mortie31]

The advanced aquarist article someone mentioned earlier...
https://www.advancedaquarist.com/2010/2/aafeature
And there conclusion
The chemical/elemental composition of skimmate generated by an H&S 200-1260 skimmer on a 175-gallon reef tank over the course of several days or a week had some surprises. Only a minor amount of the skimmate (solid + liquid) could be attributed to organic carbon (TOC); about 29%, and most of that material was not water soluble, i.e., was not dissolved organic carbon. The majority of the recovered skimmate solid, apart from the commons ions of seawater, was CaCO3, MgCO3, and SiO2 - inorganic compounds!

To me the percentages of the waste removed is pretty meaningless, if we don’t know the amount of organics actually in the tank to compare them against each other. It could be removing 100% of the TOC / DOC or next to none of them.. this analysis just tells us the breakdown of what’s removed and not what may or may not be happening to levels in the tank.. maybe Tritons NDOC test will shed some light on things

 

[Timfish]

But what amount of cryptic sponges do you need to effectively filter DOCs? Where do you get them, and can a typical aquarium keeper keep enough of them thriving to keep your water clean? . . .

Well, this is a bit facetious but only about 1/2000th of the bacteria biomass that would be needed to remove the same amount of DOC. Steve Tyree has written about this and should be given credit for recognizing the importance of sponges about a decade before Jasper de Goeij did his groundbreaking research showing sponges are recycling most of the labile DOC on reefs. Any quality wild live rock or maricultured live rock will have sryptic sponges to seed a system with. If you look behind/under your rocks you likely already have some. If you do, you might want to rethink what your carbon dosing is doing. De Geoij also showed the detritus sponges release into the ecosystem is nitrogen enriched.

 

[Biocube32]

My opinion is sometimes. Tiny systems are difficult to find sometheing that is more effective than frequent water changes. Low bioload systems of any size may not need one. High bioload systems of any size will likely benefit from one until the live coral gets so plentiful and efficient at filtering fish poop out that you are better off without one, or at least only intermittently. Until you get to that tank maturity though, a skimmer would likely be beneficial

 

[Biocube32]

My opinion is sometimes. Tiny systems are difficult to find sometheing that is more effective than frequent water changes. Low bioload systems of any size may not need one. High bioload systems of any size will likely benefit from one until the live coral gets so plentiful and efficient at filtering fish poop out that you are better off without one, or at least only intermittently. Until you get to that tank maturity though, a skimmer would likely be beneficial

 

[Timfish]

I hear that 30% vs 80% number a lot and think that is based out of an advanced aquarist article, but I would like to see that revisited. . .

Jasper de Goeij discusses Dissolved Organic Matter (DOM, synonymous with DOC) in the first chapter of his thesis on cryptic sponges on reefs. On pg 15 he gives 70-80% is refractory and the balance is labile.

 

[Timfish]

Feldman, et al, did a series of expeirements looking at Total Organic Carbon (TOC, roughly 10% POC and 90% DOC, aka DOM), GAC, skimmers and Bacterial counts in reefs. Here's the links:

Granular Activated Carbon Pt 1
http://www.advancedaquarist.com/2008/1/aafeature1

Granular Activated Carbon Pt 2
http://www.advancedaquarist.com/2008/2/aafeature1

Total Organic Carbon Pt 1
http://www.advancedaquarist.com/2008/8/aafeature3

Total Organic Carbon Pt 2
http://www.advancedaquarist.com/2008/9/aafeature2

Protein Skimmer Performance, Pt 1
http://www.advancedaquarist.com/2009/1/aafeature2

Protein Skimmer Performance, Pt 2
http://www.advancedaquarist.com/2010/1/aafeature

Skimmate Analysis
http://www.advancedaquarist.com/2010/2/aafeature

Bacterial Counts in Reef Aquarium Water
http://www.advancedaquarist.com/2011/3/aafeature

 

[Timfish]

. . . maybe Tritons NDOC test will shed some light on things

I for one would like to know what N-DOC actually is? I've searched Google Scholar and haven't found any info or explanation of what it is. I especially would like to know how it correlates to Dissolved Combined Neutral Sugars (DCNS) that increases virulence factors in reef systems.

https://www.ncbi.nlm.nih.gov/pubmed/23303369
https://www.nature.com/articles/nmicrobiol201642
https://www.ncbi.nlm.nih.gov/pubmed/23882445

 

[Scrubber_steve]

I hear that 30% vs 80% number a lot and think that is based out of an advanced aquarist article, but I would like to see that revisited. The amount my skimmer has pulled out while also running carbon and purigen is pretty amazing. Now I know skimmers also remove larger items like bacteria but it seems to me there must be something more going on. Perhaps more examination of what all skimmers remove.

Elemental Analysis of Skimmate: What Does a Protein Skimmer Actually Remove from Aquarium Water?
By Ken S. Feldman

 

[hart24601]

Elemental Analysis of Skimmate: What Does a Protein Skimmer Actually Remove from Aquarium Water?
By Ken S. Feldman

A shame it’s only on one tank. I wonder how those results would compare to several systems. I would be hesitant to draw conclusions from one system. I would also be curious to look at the foam before it’s in the cup for several days, while the elemental composition wouldn’t change but it would be interesting to see what compounds or phytoplankton/microbial life are present before sitting in the cup as one would think some will die and be consumed by others.


The results are interesting here running carbon as if the carbon is fresh it seems that almost all the DOC should have been absorbed there and not passed to the skimmer if the common statement of carbon working far better for doc removal is accurate.

 

[hart24601]

Feldman, et al, did a series of expeirements looking at Total Organic Carbon (TOC, roughly 10% POC and 90% DOC, aka DOM), GAC, skimmers and Bacterial counts in reefs. Here's the links:

Granular Activated Carbon Pt 1
http://www.advancedaquarist.com/2008/1/aafeature1

Granular Activated Carbon Pt 2
http://www.advancedaquarist.com/2008/2/aafeature1

Total Organic Carbon Pt 1
http://www.advancedaquarist.com/2008/8/aafeature3

Total Organic Carbon Pt 2
http://www.advancedaquarist.com/2008/9/aafeature2

Protein Skimmer Performance, Pt 1
http://www.advancedaquarist.com/2009/1/aafeature2

Protein Skimmer Performance, Pt 2
http://www.advancedaquarist.com/2010/1/aafeature

Skimmate Analysis
http://www.advancedaquarist.com/2010/2/aafeature

Bacterial Counts in Reef Aquarium Water
http://www.advancedaquarist.com/2011/3/aafeature

Thank you for the links! I have read those a few times over the years although it’s been a while.

What I would find interesting is skimmate analysis in a system running activated carbon and without unless I missed it in one of those links. One would think if carbon is not exhausted there would be nearly no DOC found in the skimmer, which may be the case but then I am curious about what the skimmer is removing in systems running activated carbon as it still removes a great deal of murky liquid.

I suspect the argument I hear of “skimmers only remove 30% of the doc vs carbons 80%” on the froums frequently is potentially misleading as it glosses over other items skimmers remove.

 

[Scrubber_steve]

The results are interesting here running carbon as if the carbon is fresh it seems that almost all the DOC should have been absorbed there and not passed to the skimmer if the common statement of carbon working far better for doc removal is accurate.

I wouldn't expect the carbon to remove all the DOC in a volume of water in only one pass. It would take several pass throughs, leaving a skimmer a chance to also capture its share.

 

[hart24601]

I wouldn't expect the carbon to remove all the DOC in a volume of water in only one pass. It would take several pass throughs, leaving a skimmer a chance to also capture its share.

You basing that on doc concentration vs binding data of varieties of carbon? One would think if it’s removing not quite 3x more DOC it should have bound just about all before the skimmer particularly if is in a reactor?

I wonder how much rotting or die off occurs in the cup over time as well which could give a false indication of DOC in the skimmer cup but when removed was a particle of mysis for example.

 

[Mortie31]

Feldman, et al, did a series of expeirements looking at Total Organic Carbon (TOC, roughly 10% POC and 90% DOC, aka DOM), GAC, skimmers and Bacterial counts in reefs. Here's the links:

Granular Activated Carbon Pt 1
http://www.advancedaquarist.com/2008/1/aafeature1

Granular Activated Carbon Pt 2
http://www.advancedaquarist.com/2008/2/aafeature1

Total Organic Carbon Pt 1
http://www.advancedaquarist.com/2008/8/aafeature3

Total Organic Carbon Pt 2
http://www.advancedaquarist.com/2008/9/aafeature2

Protein Skimmer Performance, Pt 1
http://www.advancedaquarist.com/2009/1/aafeature2

Protein Skimmer Performance, Pt 2
http://www.advancedaquarist.com/2010/1/aafeature

Skimmate Analysis
http://www.advancedaquarist.com/2010/2/aafeature

Bacterial Counts in Reef Aquarium Water
http://www.advancedaquarist.com/2011/3/aafeature

Thank you for these links, interesting to read Feldmans conclusions from the skimmer performance pt2 study
“The results to date on protein skimming as a means of aquarium water remediation form a consistent picture that is at odds with some of the cherished dogma in the marine husbandry area. According to the data presented in this and the earlier paper (Advanced Aquarist, January 2009), protein skimmers appear to have a much larger variation in their prices than they do in their ability to remove TOC from aquarium water. Recent design innovations like bubble plates, conical sides, or pinwheel impellers do not seem to impact significantly on either rate of TOC removal or amount of TOC removed, at least for the skimmers tested. Thus, skimmer manufacturer claims about enhanced organic removal capabilities should be met with skepticism in the absence of compelling and quantitative TOC removal data.”
This study is 10yrs old and it appears nothing has changed...

 

[steve bergmann]

Nice. May I ask how much you feed and what your no3/po4 levels are? And what export methods you use? Thanks.

I feed automatic 4 times a day and then manual once or twice a day but some days not at all. I don't have nitrates, but I don't dose for them either, that is what the fish are for. Phosphates are right in line, not too low nor too high. The system is a little too efficient for the nitrates. I figure the corals get first crack at the nitrates before the water goes into the sump which completely pretty much takes them out.

 

[ReefGeezer]

Big, mature reef tank with very few fish... maybe not.
Small immature reef tank with a lot of fish... absolutely!
Somewhere in between... Yea, I'd run one. They're simple and cheap to operate and maintain, don't cost as much as they used to, remove at least some organics from the water column, and possibly promote some gas exchange.

I've had plenty of time to read those old studies that get linked in every skimmer discussion. I gotta admit I don't understand all the scientific jibberish. That said, I don't think I'll remove mine just because a study indicated skimmers weren't terribly efficient. So what if it doesn't get it all. Removing some excess organics are better than removing none. It's also quite probable that removing all the organics is not preferable. IMO, where organic input is higher than the system can export/use, a skimmer should always be employed.

 

[Filipabp]

I've run a mixed reef with no skimmer for 8 months now (since the beginning). Only means of nutrient export other than corals etc is Rowaphos, active carbon and biohome rocks in my canister filter. Wanna know what my current problem is? Nutrients are too low.. My SPS were losing their color, and i was surprised to find nitrates and phosphates unmeasurably low.

To be honest I think skimmers may be overhyped, but not useless of course.