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Tunze 9004 Comline DOC Protein Skimmer


Item #: TZ79004

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Tunze Comline DOC Protein Skimmer 9004 (9004.000)

The new Tunze Comline® filters opens the way for compact aquarium components designed for internal operation, are ultra-functional and are highly-sophisticated. The system creates a natural atmosphere in the aquarium at a minimum size. The goal always remains the same, more performance and less space.

The Comline® DOC Skimmer 9004 is designed for use in seawater mixed aquariums / soft coral aquariums up to 250 litres (66 USgal.) or sensitive reef biotopes with stone corals up to 150 litres (40 USgal.). It works based on the TUNZE® Flash Skimming principle, water supply is provided via an efficient surface intake system with bacteria film removal. Thus, the system can also be used as a “standalone solution” in the aquarium. The featured TUNZE® Foamer generates many fine air bubbles with a diameter between 0.1 and 0.3mm, which ensures particularly silent operation.

The “Flash skimming” principle enables highly efficient foam production.
Principle: Protein-rich surface water is mixed with water thoroughly in the TUNZE® Foamer. On the surface of the air bubbles forming, pollutants such as protein, cellulose, dead cells, etc. are adsorbed immediately, the air bubbles are very fine, with a diameter between 0.1 and 0.3mm. The water/air mixture is expanded and stabilized in the skimmer cup, the water returns to the aquarium, and the protein-loaded air bubbles reach the skimmer cup reactor. The patented anti-overfoaming system intermediate chamber with phase water prevents the skimmer from overfoaming and controls the skimmer performance, depending on the water level and organic load.
The particularly high efficiency of the “flash skimming” principle compared to large skimmers with long contact time is obtained because the substances adsorbed by the air bubbles are not released again, thus they don`t return to the aquarium water again.

  • Surface intake with bacteria film removal.
  • Skimmer cup, 0.2l (.05 USgal.) volume, also accommodates the foam reactor, easy to remove.
  • Attachment with a patented magnet holder for a glass thickness of up to 3/8".
  • Intermediate chamber with patented anti-overfoaming system.
  • TUNZE® Foamer 9004.040, high air output and low energy consumption (4W).
  • Bubble-free outgoing water.
  • New “Comline® Design”: comfortable use, elegant and unobtrusive in the aquarium.
  • Air flow regulation and silencer for an exceptionally quiet operation.
  • Made in Germany, 2-year manufacturer`s warranty


  • Dimensions: 4.3" x 3.5" x 12"
  • Water Lever Required: Approx. 8.86" - 9.65"
  • Air Output: Approx. 150 L/H
  • Energy Consumption: 4W
  • Tank Size: 15-65 gallons
  • Mounts aquariums up to 1/2" thick

Includes magnet mounts

Manufacturer information

For forty-five years the name TUNZE® has been synonymous with aquariums. Many products and components which we have developed in the course of time are now standard features of aquarium technology today. This confidence in TUNZE is no coincidence. The company has remained true to its philosophy right from the beginning, researching water biotopes all over the world to develop components which enable natural water conditions in the closed environment of an aquarium. In the implementation of know-how, effectiveness and efficiency, TUNZE® takes the lead in environmental compatibility. Their motto is: quality and reliability. These values are upheld with well thought-out and precise tool making by highly qualified experts. The brand names of TUNZE® and Turbelle® meet the expectations of the seal of quality; Made in Germany. Many of the products shown in this catalogue are protected by national and international patents.

4 Stars


Reviewed on
January 04, 2021

AIO Skimmer

Pros: See above - adequate, if you are patient and can’t use a HOB type skimmer

Cons: See above - have to give neutral recommendation.

Pros: fits nicely in the JBJ 65 gal rear compartment. Well made
Cons: very long run-in time to properly tune, Dreading disassembly for cleaning.
Comments from others are not accurate. For example, this is not a quiet skimmer - air production is definitely audible and is quiet only when turned off.
Comment:Immediately skims out of box - this is just wrong, unless overproduction and rapid filling of cup equates with skimming, which it does not. Getting this adjusted has taken over 2 months, patience is necessary, attempting to reduce air inflow causes very loud clicking noise. Best option is to adjust skimmer height by millimeters - start at a level where barely any foam enters chamber and gradually lower the device until foam just begins to reach top of cup. Even then, it will take time (days) to get this right, to begin production of true skimmate which will be be dark, semi-sludge-like, and smelly. Guess I was used to my Octopus skimmer on a 160 gal reef I previously owned.
I was very tempted to either return it (which Marine Depot would graciously accept) but will stick with it as I hope it is finally adjusted.
Just don’t expect quick results. Maybe the DOC model with the controller would be better but it is always out of stock.
Only other option might be a HOB model.

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Reviewed on
April 18, 2020

Yes, I would recommend this.

About the best Nuvo 40 option

Pros: Fits in back of nano tanks. Clean look, quiet.

Cons: Taking it apart to clean and reassembling can be a bit taxing.

As some of the other reviewers note, this can be a bit of a pill to take apart. It's just that the disassembly and assembly is a bit counterintuitive. I had used this on an old Marineland 27 cube, got frustrated with it and put it in the garage. But, when I upgraded to a Nuvo 40, I discovered that this was one of my few options for something that would fit in one of the back chambers and not loom above the tank like the Aquamaxx HOB. At any rate, I hauled it out, took it apart, cleaned it thoroughly with vinegar and water, assembled it again (with the aid of a youtube video and a minimum of gratuitous profanity), stuck it in the right return chamber, and it seems to be working well. Any skimmer on a tank this size is something of a bonus anyway, since none of them work that well and don't remove that much waste. At least this one has a clean look and is super quiet. I'll add that Tunze's customer service is first rate should you have need of it.

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Reviewed on
March 07, 2020

No, I would not recommend this.

Was hoping for better

Cons: Price, cleaning and putting back together, Magnets

I've had this skimmer for over a year and it just doesn't seem like it's worth it for the money. It's a pain to clean and put back together. Any suggestions for something better?

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Reviewed on
February 23, 2020

Yes, I would recommend this.

Works well after some trial and error

Pros: Works well once you figure it out

Cons: Took almost a year to figure out removing collection cup lid would drastically dry out the skimmate. Maybe that's my problem.

I bought this skimmer a little over a year ago. As the title says it takes some fiddling. Once you figure out the best level to mount it. The skimmate will be really dry if you stop using the lid on the collection cup.

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Reviewed on
April 04, 2019

No, I would not recommend this.

Tunze skimmer

Pros: skims protein when assembled correctly

Cons: cannot be assembled correctly

I am writing this almost a year later so maybe things have improved. In summary, in over 50 years of aquarium keeping, this is the only aquarium product which I threw into the trash. The only thing better than the actual tossing was the feeling of relief which filled me afterward. How can I explain it? Well, if you like Rubic's Cube then you may enjoy trying to re assemble this unit after cleaning. I think it worked ok as a skimmer. I figured hay German technology it has to be good. I was wrong on this one.

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Reviewed on
March 26, 2019

Yes, I would recommend this.

Great Compact Skimmer

Pros: Compact, Quiet, Removes Everything

Cons: Magnet Clips & Wetter Skim

If you're looking for a compact skimmer that will really get the job done, I definitely recommend this skimmer. I have it in my 29g sump of my 40 breeder and it does a great job pulling everything out. Its quiet and definitely produces some serious foam. Clips that hold magnets in place break easily so be prepared to glue the magnets on but the performance far outweighs the need to glue. This skimmer does produce a more wet skimmate even when air is cut down to almost nothing. I am going to try to adjust the height slightly to get a thicker skim but either way, I love this skimmer.

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Reviewed on
March 26, 2019

Yes, I would recommend this.

Great Nano Skimmer But Skimz Wet

Pros: Skims Great, Quiet, Easy Setup & Maintenance, Space Saving

Cons: Magnet Clips & Wetter Skimmate

This skimmer has been a beast on my 40 Breeder setup which is about 50/55 gallons total volume. My only complaints are that the clips for magnets break too easily and it skims pretty wet even with air closed off completely. I may have an older model so if they fixed the magnet clips I would say it's perfect for any nano tank out of the box.

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Reviewed on
March 25, 2019

Yes, I would recommend this.

Skimmer for AIO

I bought this for my IM Nuvo 40. It worked well but I needed something more so I had to replace it. These work great and skim perfectly!

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Reviewed on
May 18, 2018

Yes, I would recommend this.

Nice product

Nice product SA Testing

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Reviewed on
February 20, 2018

No, I would not recommend this.

Tunze skimmer

Pros: Size

Cons: Price, operation, adjustability, design.

I bought this skimmer hoping it was good quality. After 20 days of operation the motor stopped on me. It was a pain to install and the adjustments were very awkward. The water level has to be within about a quarter inch were to work properly. I am very disappointed in this product.

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