Cobalt MJ1200 Powerhead

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Cobalt MJ1200 Powerhead

84% Recommend this to a friend (38 of 45)

SKU: 210504
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Quick Overview

Why does BRS recommend this?

The Cobalt MJ line of pumps is great for auto top off systems, reactors, or low flow equipment.  These pumps are made in Italy and are much quieter in operation than similar pumps that appear to be identical.  With so many applications the Cobalt MJ pumps have some of the best value for a submersible pump. 

  • Flow Rate: 295 GPH

  • Maximum Head Pressure: 69"

  • Power Usage: 20 Watts

  • 3 Year Warranty


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Product Questions

In using this with your mini reactor, is the pump large enough to push the water from the display down 35 inches, (inside the stand) then back up the 35 inches back to the tank? Or should I be looking at something larger? The tank is only 45 gallons and is an all in one, hence why I want to put it in the stand, (back siphoning an issue I am aware of).
Question by: Lola on Jan 31, 2016 4:42:00 AM
Great question!
In this pump it has a maximum head height of 69" meaning the flow after pushing the water back up 35" will be greatly reduced. We would recommend a larger pump if possible such as a Sicce 1.5. I have included a link to the pump as well as the adapter to connect the pump to the reactor tubing.

1⁄2" Male NPT x 1⁄2" Push Connect
SKU: 100003

Syncra Silent 1.5 Pump (357 GPH) - Sicce
Answer by: Connor (Admin) on Feb 10, 2016 3:13:00 PM
Can this be used as an external pump if you plumb the input?
Question by: Aaron on Jan 22, 2016 11:20:00 AM
Great question!
This could be used externally however plumbing it would prove to be a challenge as it does not use barb or threaded fittings and would need 1/2" ID tubing to connect to it. Keep in mind this cannot pull water, only push, so when plumbing the water will need to naturally feed into the pump. Feel free to let us know if you have any further questions!
Answer by: Connor (Admin) on Jan 28, 2016 1:44:00 PM
Im looking at this pump to replace my Rio on the CPR bakpak skimmer, does this come with everything need it make it work. Im gonna be honest I'm not the best at mods. Thank you.
Question by: Adam on Jan 22, 2016 6:48:00 PM
Great question!
This pump will come with a standard impeller and will not work as a skimmer pump unfortunately. If you have a replacement impeller which can work in a MJ1200 this may work? Feel free to let us know if you have any further questions!
Answer by: Connor (Admin) on Jan 28, 2016 3:34:00 PM
As I need to ensure that space is available within my existing sump, what are the "footprint" dimensions of the MJ-1200 pump?
Question by: Patrick S. on Apr 14, 2014 12:21:00 AM
Hey Patrick,
Assuming the output is up and your not using any of the suction cups, brackets, etc the pump is about 2" wide and 3.5" across, though keep in mind with that later number you will want some extra room so the water can actually enter the volute so I would go with more like 2x4 at the least.
Answer by: Bulk Reef Supply on Apr 14, 2014 12:21:00 AM
What is the output size on this pump?
Question by: Jacob on Mar 22, 2014 5:29:00 AM
Hi Jacob,
The output size of the pump is the same as 1/2" polyethylene tubing like those used with our reactors (which is a slightly different standard then 1/2" PVC). A 1/2" push connect union for example will snap right on.
Answer by: Bulk Reef Supply on Mar 22, 2014 5:29:00 AM
If you're using this pump as part of your ATO system, what is the size of the output? I'm getting the Hydor ATO system and this pump was recommended by you. I would like to get the correct size tubing before I get the pump and set up the system. Thanks.
Question by: David on Apr 5, 2014 4:52:00 PM
Hi David,
The MJ1200 has an output that is actually the same size as 1/2" RO tubing, so conveniently you can actually use a 1/2" push connect union on the end to connect the pump to 1/2" ro tubing just like we do with our BRS reactors.
Answer by: Bulk Reef Supply on Apr 5, 2014 4:52:00 PM

Full Details

The Cobalt Aquatics MJ series of pumps is the same Italian-made MJ you have been using for the last 20 years. Reliability and low operating noise have been the staple of this pump series, a principle reason why aquarists around the world have been using them for decades. After the original MJ distributor moved operations to China, Cobalt Aquatics jumped on the opportunity to work with the Italian manufacturer to continue to provide a source for this high quality product line. Mostly used for wave makers, protein skimmers, calcium reactors, nano aquariums, under gravel filters and hydroponic applications.


  • Fully rotational output
  • Fully sealed intake for internal and external use
  • Universal intake tube Adjustable hanger with cord guide and 6 Ft power cord
  • Adjustable venturi with silencer
  • Triple suction cup mount
  • Large intake screen for use with sponge

Quick Compare - Cobalt Aquatics MJ Powerheads

Model Flow Rate Maximum Head Pressure Watts
Cobalt MJ400 106 GPH 29" 5

Cobalt MJ600

160 GPH



Cobalt MJ900

230 GPH



Cobalt MJ1200

295 GPH





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  • Failed after 3 weeks of use By Scott on 4/7/2016

    Maybe I just got a bad one, Mine failed after less that 3 weeks of use. I contacted cobalt directly, they said I should soak the impeller in vinegar for an hour, I did that it still did not work. Soaked it for a full day. Still did not work. Called cobalt back and they said they would send a new impeller. That was almost four weeks ago, still no new impeller
  • Great pump! By juschillin2 on 3/7/2016

    Works exactly as described. Very pleased powerful AND silent. Highly recommend!
  • Great Product! By Christopher on 3/7/2016

    This pump is unbelievable! Super Quiet! small footprint considering mine sits in the tank.
  • Great pumps By GLC on 12/16/2015

    These are tried and true workhorse pumps. I use them for multiple purposes and they are extremely dependable and quiet. The Cobalt brand is much quieter and the build quality is superior to the Marineland version.
  • Good Buy By Greg on 12/13/2015

    Works great ....Perfect for my carbon/gfo reactor.
  • So far so good! By Adam on 12/12/2015

    I purchased this power head to power my BRS dual reactor. So far, it's quite and works as advertised. So far so good!
  • Workhorse By Virgil on 11/30/2015

    I have 3, my oldest has been running for 3 years with no problems
  • Good product By R.l on 8/11/2015

    Great flow , runs silent
  • died By Jonathan on 7/9/2015

    quit working after 6 months
  • Versatile By kyle on 7/7/2015

    Lots of nice accessories for attaching tubes or for direct return I side tank.
  • Impressed By Cora on 6/9/2015

    Replaced the stock pump on my JBJ 20 which was 265 gph for the Cobalt 1200 295 gph, big improvement in flow and this pump is silent. Very happy with the result. Fit perfectly in the back compartment.
  • Perfect! By Tony on 4/11/2015

    I received this pump first with my order of the BRS GFO&Carbon reactor, and its a great handy little pump. I have recently ordered a second one that I will be using as a transfer pump for water storage.

    Its a great pump for many applications!

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