Comline DOC Skimmer 9004 - Tunze

Tunze Comline DOC Skimmer 9004
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Comline DOC Skimmer 9004 - Tunze

88% Recommend this to a friend (15 of 17)

SKU: 208412

reg. $153.77

Special Price: $107.64

In Stock: 39
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Quick Overview

Why does BRS recommend this?

We have really liked the Tunze Comline skimmers due to their small form factor and their ability to adapt to many different systems. With AC pump and DC pump models available you can choose the skimmer that works best for your system.

Using the Tunze Flash Skimming Principle, the Comline DOC Skimmer pulls water through an efficient surface suction.

Heavy Bioload - 20 gallons

Medium Bioload - 40 gallons

Light Bioload - 60 gallons

  • Up to 65 Gallon tank (Depending on tank load)

  • Skimmer Cup volume: .2 Liters

  • Air capacity: 40 GPH

  • Magnet holder for up to 1/2" thick glass

  • Quiet Operation

  • Bubble free outgoing water

  • Easy to remove collection cup

  • Immersion depth: approx. 225mm to 245mm (8.86 to 9.65 in.)

  • Power consumption: 4W, 230V/50Hz (115V/60Hz)

  • Dimensions: L110 x W90 x H305mm (L4.3 x W3.5 x H12 in.)


Full Details

Owners Manual


The Tunze Comline DOC skimmer utlizes Tunze's "Flash Skimming" principle. The skimmer is quiet and generates a very large volume of small bubbles for efficient skimmer operation. It operates stand-alone without needing any additional equipment (feed pumps, etc) and mounts to the tank via a convenient magnet holder strong enough for glass up to 1/2" thick.

The TUNZE® Foamer generates large volumes of fine air bubbles with a diameter between .0039 to .011 in. (0.1 to 0.3 mm) On the surface of the air bubbles, pollutants such as protein, cellulose, dead cells, etc. are adsorbed immediately. The water/air mixture expands and stabilizes in the skimmer cup reactor, the water returns to the aquarium, and the protein-loaded air bubbles spill over into the skimmer cup. The patented anti-overfoaming system intermediate chamber prevents the skimmer from over foaming and controls the skimmer performance, depending on the water level and organic load. This “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.


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  • Clogs on a regular basis By Robert on 9/7/2017

    Look for another skimmer unless you're a tunze fanboy or love fidgeting with your tank components. You will have to unplug it regularly (daily) to prevent clogging. If you ask for advice, you get vague answers like: raise or lower it, move the intake away from the back of the aquarium. Whatever...I've had this skimmer for a couple of years and can't wait to replace it. Way overpriced, too.
  • Good Skimmer but... By Steve on 8/11/2017

    Overall this skimmer does a good job on my 20 gallon tank. It is very quiet, and collects a good amount of wet skimmate. On the negative side: It produces a lot of micro-bubbles. They come from the seams between the front plate and the body, and there doesn't seem to be anyway of stopping it. Also, the front plate can be difficult to remove for cleaning. You have to push in hard on the plastic tabs holding the front plate to the body, and every time I've done this I worry about breaking it. So far so good. But I have managed to cut myself multiple times as the front plate suddenly flies loose.
  • Microbubble machine! By Steve on 6/30/2017

    This is the first Tunze product that I've been really disappointed in. I'm surprised more people aren't talking about this issue in the reviews here. A simple Google search will show the issues with this skimmer. It is an absolute microbubble machine. The height adjustment of this skimmer is really finicky, and unless you have a quality ATO, pass on this skimmer. I checked that my pump and skimmer plate were installed correctly. That didn't work. I placed a foam insert on the bottom. That didn't work either. And unless there are surfactants in my water column that I don't know about, that shouldn't be the problem either. Given, I understand that these skimmers have a break in period, but at what cost when I can't even see what's in my tank due to the sheer amount of microbubbles. Furthermore, I've owned a plethora of skimmers in the past. A solitary break in period for this skimmer will NOT be enough to minimize the amount of microbubbles this thing produces.

    I'm not a believer that microbubbles cause any issues for fish or coral, however, when this skimmer created a large amount of them in my tank, two of my fish started to flash wildly against the sand bottom. This baffled me as it was the first time I've witnessed that.

    On a positive note, this skimmer seems to be made of decent quality materials, sans the extension pieces for the magnets. Those are very, VERY poorly made. The skimmer is also extremely quiet. You also won't get a nice dry skim out of this thing, but it did pull out a decent amount of gunk through a wet skim.

    Perhaps I got a bunk product, and you might have better luck with this skimmer than I did. I do believe that Tunze makes excellent products. Just not this one.
  • Mini horse By Andrew on 5/4/2017

    Although I do have a couple of complaints this skimmer still deserves 5 stars. 1: That air tube fell off during shipping but the excellent usa customer service handled it spot on. 2: collection cup is on the small side but the overall footprint is so small I wasn't expecting anything more. 3: that air control valve is just a simple screw that pinches the air tube when screwed in clockwise, simple and effective but I feel as if it will wear the integrity of the tube over time.
    Didn't require more than a day of break in time and this thing is producing some nasty (good) skimmate. I would buy this skimmer 10 times if I had to.
  • Great skimmer for a tank without an overflow By Andrew on 4/25/2017

    Bought this for a 40 gallon tank that didn't have a skimmer or an overflow. As a result, there was a surface slick of waste that was preventing light from penetrating to the bottom of the tank. After installing this skimmer, the surface slick was gone in about a week (skimmer took about three days to settle down) and the water is generally much clearer. Very happy with my purchase, great value for money. very silent, energy efficient, yet powerful and easy to clean. Will make this my go to skimmer for all tanks less than 50 gallons, especially if the tank doesn't have an overflow.
  • Worked like a charm By Alfred on 12/13/2016

    I bought a complete reef set up that came with a skimmer but alas, it was giant for this small 30gallon (sump included). I finally decided to throw the money at a new one and this one offered the perfect space saving to proper skimming ratio my tank needed. It fits nicely into my small sump and even leaves room for me to integrate a tiny refugium. To add to it, it skims great and my corals look happier than ever
  • Great protein skimmer By Matt on 9/23/2016

    I needed a protein skimmer that did a good job, wasn't too expensive, and was quiet due to the fact my tank is in my room. I was not disappointed.
  • Best Nano Skimmer I've Used By Andrew on 6/9/2016

    I have been using this skimmer on my IM Nuvo 38. I switched from the IM Aqua Gadget skimmer I had on this tank. The Aqua Gadget skimmer required constant adjustments. This skimmer is working great, hasn't needed any adjustments after the initial setup and is quiet.
  • Big Power in a Small Package By Chris B on 5/6/2016

    I have a 58 gallon Oceanic tank which is basically a tall 40 gallon footprint. Because of this size restriction I initially was running a BH1000 Reef Octopus hang on skimmer that just killed the aesthetic of the display portion of the tank, even if it was working great, it had to go. With the small size of the Tunze, I was able to put this in my sump which is otherwise devoid of space for a traditional skimmer. Although I am at the very top if not exceeding the size rating of this skimmer, I am running a relatively low nutrient system, but not ULNS by any means, with 6 fish and full CUC that is fed well daily. This skimmer is doing a great job all around. It took only about 2 days to break in fully, 3 days to tune, and pulls great skimmate consistently. The footprint compared to performance is amazing. The only minor complaints are in the reassembly after teardown and how short the breather line is. I wish it was set up for another 3-5 inches to place in comfortably out of my sump chamber. I could extend it, however they recommend against it, and I haven't had time to tinker yet.
  • Great By Kevin on 2/16/2016

    Best nano protein skimmer I have ever purchased. I am using it on my JBJ 30g rimless and fits perfectly into the first chamber. Does an awesome job!
  • Great product. Some minor issues By Dhero5 on 1/12/2016

    When I received the product I followed the instructions which were pretty straightforward and simple. Once I plugged it in nothing happened. I did a little research and found out it's very common for the hose disconnects from the pump in shipping. I took the device apart and sure enough that is what happened. I put back in the tank and it worked except I had a ton of micro bubbles in the tank. I did some more research on the position of the pump since the book doesn't explain how it should be positioned. I found a picture thT shows the pump attached to the front cover which made sense and worked. The pump has been operational for 2 weeks. I still have some bubbles but that is expected since it is in the tank. One problem I noticed out of the box was the magnet extenders are cheaply fastend to the body by clips. One clip arrived broken and the other ended up breaking so they are glued to the body now. The magnets are not as powerful as I expected so they do both old the unit super solid but it works.
  • Perfection By Brett on 8/20/2015

    This is on a JBJ 45 gallon rimless aquarium with the AIO sump on the back. Fits like a glove. Works amazingly.


Ask a question

Product Questions

hey guys! im planning to set up a 60 gal reef tank with some nice corals, anemones and clown fish and others... i don't know which skimmer will fit best...

Tunze Comline DOC Skimmer 9004 or Reef Octopus BH2000

what would you guys recommend buying?

thanks a lot

Question by: ViKo on Jul 10, 2014 9:06:00 PM
Hi ViKo,
If it is between these two skimmers my preference is for the Octopus. I really like the Tunze skimmer it just happens that the Octopus is rated for a much larger tank and when it comes to skimmers, I would always get the biggest one that fits in your budget and space constraints.
Answer by: Bulk Reef Supply on Jul 10, 2014 9:06:00 PM
Will this fit on my Coralife Biocube 14?
Question by: Ryan on Nov 4, 2016 10:50:00 AM
Hey there! Unfortunately, this will not fit in that BioCube chamber. :-(
Answer by: Randy (Admin) on Nov 4, 2016 12:18:00 PM
Would this skimmer be sufficient with the Fluval M60 AIO aquarium?
Question by: Zak Payne on Jun 13, 2016 9:29:00 PM
Great question!
This will be a great fit as far as performance of a system of that size! You will want to confirm that the skimmer footprint will match the tank.
Answer by: Connor (Admin) on Jun 15, 2016 2:12:00 PM
Will the 9004 fit in my IM Fusion 40 gal.
Question by: Capt. Sergio Atanes on Jan 26, 2016 5:43:00 PM
Great question!
The 9004 will just fit in the overflow section however this will restrict the overflow compartment as well has having height issues. While it may work we recommend the IM midsize ghost skimmer as an alternative which is designed for the tank. Feel free to let us know if you have any further questions!
Answer by: Connor (Admin) on Feb 3, 2016 3:31:00 PM
My skimmer was doing well for about 8 months and then started acting very funny after a water change during which te skimmer was temporarily turned off. The problem is that micro bubbles are pouring our of the bottom and the collection cup fills with water almost immediately. Adjusting the air hasn't yielded good results. Any suggestions?
Question by: William Moss on Feb 9, 2016 10:22:00 PM
Great question,
Some quick fixes may include changing the height of the skimmer in the water. Making sure no other changes have occurred as well such as different bio-load or other adjustments to the skimmer cup itself. Feel free to let us know if you have any further questions!
Answer by: Connor (Admin) on Feb 10, 2016 12:46:00 PM
Would this fit in a nuvo 30L?
Question by: Eric on Feb 1, 2016 1:23:00 PM
Great question!
The Tunze skimmer actually mounts from the side and would not fit well by mounting it in the tank. Ideally the Midsize Ghost skimmer by IM is the ideal shape and size for your tank. Feel free to let us know if you have any further questions!
Answer by: Connor (Admin) on Feb 19, 2016 9:33:00 AM
I didnt actually mean to buy this skimmer but if it works in my Coralife biocube 29 I will gladly use it. Any idea if it will fit in my biocube 29?
Question by: Dave on Apr 20, 2016 7:16:00 PM
Great question!
Unfortunately we do not have the dimensions of the Coralife tank however the skimmer dimensions are (L4.3 x W3.5 x H12 in.)
Answer by: Connor (Admin) on Apr 26, 2016 2:21:00 PM
Will this fit in in the back of a Nuvo 16?
Question by: Brian on Apr 27, 2014 7:24:00 AM
Hi Brain,
Unfortunately it would be too large to fit in the back of a Nuvo 16.
Answer by: Bulk Reef Supply on Apr 27, 2014 7:24:00 AM