Reef Octopus Classic 110EXT 4” Recirculating Protein Skimmer

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Reef Octopus Classic 110EXT 4” Recirculating Protein Skimmer

85% Recommend this to a friend (11 of 13)

SKU: 204064
In Stock: 4
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Quick Overview

BRS Recommended for tanks up to:

Heavy Bioload (Most Common) - 65 Gallons

Medium Bioload - 100 Gallons

Light Bioload - 130 gallons

External protein skimmer powered by Aquatrance 1000 pump with an improved venturi design and pinwheel impeller. Built with high-quality acrylic. Wedge pipe output allows for more adjustment of the skimmer compared to ball valves. ½” clearance required to remove collection cup for easy cleaning.

Footprint - 10.4" x 9.25"

Height - 22.8"

Feed Pump Required - 120 to 260 gph recommended


Full Details

Classic EXT Skimmer Setup Guide


The Classic 110EXT skimmer requires a feed pump to feed water to the skimmer. The recommended maximum flow rating for this skimmer is 260 GPH. These numbers are based on zero back pressure on the output plumbing. If you add 90° bends on the plumbing back to a sump you may need to back off the amount of water being feed through the skimmer. We recommend that you use a ball valve inline from your feed pump to the skimmer allowing you to control the water flow.

  • High performance venturi air injection system
  • Modified cone neck design designed for easy transition of micro bubbles into cup
  • Requires a feed pump or plumbed from an overflow to inject water into skimmer
  • Can be in sump or external
  • Metric plumbing parts.
  • 1 year warranty on skimmer and pump


Note: A feed pump is required that can flow around 1.5 - 2 times the systems volume. We suggest a pump around 150 to 250 GPH, and particularly like the VarioS 2 Controllable DC pump or Sicce Syncra Silent 2.0, we also highly recommend a gate valve to help control and fine tune the flow of water into the skimmer from the feed pump.


Filtration Handling

Well Stocked Tank - Rated up to 65 gallons

Medium Stocked Tank - Rated up to 100 gallons

Light Stocked Tank - Rated up to 130 gallons


Skimmer Specifications:

  • Body Diameter: 5"
  • Neck Size: 2.5"
  • Foot Print: 10.4" x 9.25"
  • Total Height: 22.8"
  • Output Size: 40mm - 1.25”
  • Inlet Size: 1/2"


Aquatrance 1000s Pinwheel Pump Features:

  • Air Draw: 420 L/H*
  • Power Consumption: 9W

*Aquarium set up will determine air and water results.


What's Included?

  • Classic 110EXT Protein Skimmer
  • Aquatrance 1000s Pinwheel Pump
  • Output Gate Valve
  • Metric to Standard Adapter


Items 1 to 12 of 13 total

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  • This thing is a beast By David on 5/2/2017

    This is my third skimmer since I started the hobby but first recirc. let me tell you I will always use recirc skimmers. This thing is very easy to tune... VERY easy. It does a far better job producing skimmate than my internal skimmers ever did. fantastic amount of consistent foam regardless of water level in my sump. love it. Had a challenge plumbing it but they included a metric to imperial converter that helped quite a bit. anyway... I highly recommend.

    One quick note... I did have a bad impeller at first but customer service got me a replacement within 48 hours and it has worked 100% ever since. Love it.
  • Simply The Best By Fahid on 4/21/2016

    I have used a Reef Octopus skimmer for years. I had my original one begin to leak after 8+ years of usage and decided to upgrade to this new version. The new pumps are much quieter and it only took 4 days to break in. The new valve system is super easy to control and adjust. Simply the best skimmer you can purchase based on price and quality
  • Poor materials By 70GRimless on 2/13/2016

    First off, be aware you will probably need a hacksaw for cutting METRIC pvc piping, there is NO METRIC pvc piping at your local hardware store so you are stuck with this red piping that comes provided. Also the image is misleading... the pump doesn't touch the ground, it hangs. The union arm between the external pump and skimmer leaks. They even sent me a 2nd unit because the first flooded my floor and this one still leaks. If you buy this junk be prepared for a long headache during installation. EPOXY for those unions might slow the leak but the leak will persist and find some way of dripping.
  • Great Skimmer By Sidewinder on 4/20/2015

    So far its been running around 12 days and is pulling some nice dark skim. The skimmer itself is very good quality runs super quite and was easy to put together. The only complaints I read about was about the plastic tubing. Saying it is hard to cut without smashing the tubing and that the tubing did not fit together tight. Also that the tubing is metric. First I found the tubing easy to cut with a hacksaw. I also glued the pvc with pvc glue but did not find the tubing to fit lose at all. The pipe should be guled if using external! I am using this externally but left the pipe unglued at the last bend for cleaning b/c its over my tank if it leaks. But it has not leaked! And if needed there is 2 different size metric to standard adapters included. Im very impressed with this skimmer and would recommend it to anyone looking for a inexpensive external protein skimmer 
  • This skimmer is Great By Reef Lover on 1/21/2015

    Great skimmer is great. Work as it supposed to. For everyone complaining about loose parts, there is a provided metric conversion fitting for a reason. The provided parts fit perfectly and can be extended by using normal hardware store pipe and fittings using the metric conversion fitting.
  • excellent skimmer!!! By Robert on 3/16/2014

    This skimmer is great. This is the third reef octopus skimmer I own and once again they hit the mark. Now if any of you are wondering why the pipes and fittings that come with the skimmer are lose when you put it together is because they are supposed to be glued together. That is the whole purpose of having a recirculating skimmer. If you didn't know that then you probably shouldn't be buying this product. Once again excellent skimmer not a single bad thing I can say about this skimmer. Thumbs up!!!!!
  • Odd pipe fitting, great skimmer By Crystal on 12/29/2013

    The pipes don't fit together as snug as regular schedule 40/80 pvc. This is a minor pain when setting it up because it tends to fall apart while you are attempting to get the pieces in place before gluing them. You do need a thicker application of glue than normal. I'm slightly worried about that long term as saltwater slowly eats away at the glue. If you've ever taken down a tank that has been up for 5+ years, and you give the fittings a good whack they'll come apart because of this, even though the pipes aren't leaking beforehand.
    As far as skimming, it works like a champ.
  • Very difficult to set up. By Lady A on 6/24/2013

    First, this is an external skimmer. I bought based on the fact it said it could be used either in or out of my sump. So after rearranging my wires to make room it barely fit. This is a skimmer that requires you to have a PVC cutter, PVC glue and Teflon tape. The pipes are loose and you have to use a lot of PVC glue to prevent leaks. Also I had to Teflon tape all the places where I had an o ring. That said it looks like and awesome skimmer and will see how it does after a few days.
  • Works Great By skimmer user on 4/3/2013

    The pipe fittings were a little loose, but nothing a generous application of PVC cement couldn't fix. Plastic pipe was thin walled and a bit challenging to cut since my normal cutter was squashing the pipe instead of cutting it. Assembly was easy although the directions were nothing to write home about. Was producing wet foam within 2 hours and good skimmate by the next day. Has been pulling tons of crap out of my system. Was able to install behind my refugium since there was no room in the sump.
  • High quality; easy to fine tune By David on 2/28/2013

    I got this because recirculating skimmers do not depend on the water level of a sump and my sump is a regular 20g aquarium with no partitions. It is perfect. Very easy to fine tune and efficient. skimmate globs in 2 days. It does require some glueing/assembly and it's a bit large. I'm not really sure where they got the 4" from.
  • Easy to install! By Plumber on 2/21/2013

    The exit return is long so you can cut it to length using virtually any cutting tool short of nail clippers. The parts fit together loosely because they are meant to be glued together once everything is fit to your tank. That's what you do with PVC.
  • great upgrade By James on 2/16/2013

    I upgraded to this from a nw110 when I installed a new fuge in my sump and needed to install the skimmer internally. Since it is more or less the same model I expected similar performance but this is at least twice as effective. The recirculating design produces a much thicker foam. The return pipe that came with it wasn't long enough for my install but it did come with a metric conversion fitting so I could use my own PVC.


Ask a question

Product Questions

Is there a way that I can I increase the flow rate to 300 gph?
Question by: Owen on Nov 24, 2013 5:53:00 PM
Hi Owen,
You can use a faster pump and then slow that pump down manually via a ball valve or something similar. You don't want to actually run more water threw the skimmer then recommended though. That will generally lead to reduced contact time, more escaped micro bubbles, and often an overflowing skimmer.
Answer by: Bulk Reef Supply on Nov 24, 2013 5:53:00 PM

I want to run this completely out of water. I don't mind having a second pump. First, can I do this? Second, is there anything special that I need to do? Third, what pump should I use?


Question by: Stan Rosenberg on Nov 24, 2016 8:05:00 AM
Great question! The beauty if external skimmers like this is that they can be used inside the tank or externally. The plumbing connections to the skimmer are included, however you may need additional plumbing parts for your particular setup requirements. We suggest a pump around 150 to 250 GPH, and particularly like the VarioS 2 Controllable DC pump or Sicce Syncra Silent 2.0, we also highly recommend a gate valve to help control and fine tune the flow of water into the skimmer from the feed pump. :-)
Answer by: Randy (Admin) on Nov 25, 2016 7:58:00 AM
I dont have a sump. I use a fluval 406 canister filter. How do I run water to this skimmer from my tank and then back to the tank?
Question by: Chris Meyer on May 8, 2014 11:12:00 AM
Hi Chris,
Unfortunately you can't, at least not unless you find a way to put the skimmer up higher then your tank as recirculating skimmers drain back to the tank via gravity. For a sumpless system skimmer options will be basically limited to the hang on back skimmers like the BH series skimmers from Octopus:
Answer by: Bulk Reef Supply on May 8, 2014 11:12:00 AM
What is the height of bottom point of output pipe?
Question by: Alex on Jul 21, 2016 1:48:00 AM
Hi Alex,
The bottom of the output on the 110ext skimmer is approximately 9.5” tall.
Answer by: Charlie (Admin) on Jul 21, 2016 8:02:00 AM
if I was going to put this skimmer in my sump, what depth of water should it sit in?
Question by: Chad on Apr 22, 2016 1:07:00 PM
Great question!
As long as the water is below the output of the skimmer and above the intake it will work well!
Answer by: Connor (Admin) on Apr 26, 2016 6:36:00 PM
What do I need to run external?
Question by: Aaron on Oct 11, 2013 2:43:00 PM
Hi Aaron,
You will still need a supply pump to supply water to the skimmer but if you want to physically set the skimmer in your sump, that isn't any issue at all.
Answer by: Bulk Reef Supply on Oct 11, 2013 2:43:00 PM
Is this model the dnw or dnwb? I believe the dnwb is external and is this the internal one? Or are they both the same?
Question by: Nicholas on Mar 26, 2014 10:58:00 AM
Hi Nicholas, this particular model (the DNW110) is the DNWB series of skimmer. They are recirculating models of skimmers. Recirculating models can also be used externally if your space and equipment accommodates that, though that is just a side effect of the recirculating action of the skimmer :-)
Answer by: Bulk Reef Supply on Mar 26, 2014 10:58:00 AM
The dnw110 requires a 250 gph feed pump for external but I have a 243 gph feed pump. Will that be okay?
Question by: Nicholas on Mar 25, 2014 7:50:00 AM
Hi Nicholas,
That would be just fine :-)
Answer by: Bulk Reef Supply on Mar 25, 2014 7:50:00 AM