Cobalt MJ400 Powerhead

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Cobalt MJ400 Powerhead

100% Recommend this to a friend (6 of 6)

SKU: 210500
In Stock: 38
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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: 106 GPH

  • Maximum Head Pressure: 29"

  • Power Usage: 5 Watts

  • 3 Year Warranty


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

ModelFlow RateMaximum Head PressureWatts
Cobalt MJ400 106 GPH 29" 5

Cobalt MJ600

160 GPH



Cobalt MJ900

230 GPH



Cobalt MJ1200

295 GPH




6 Items

  • Reliable very adaptable strong flow rate By bluray on 10/12/2017

    All around solid pump from Cobalt. I use it for ATO. Very reliable.
  • Works right By Trojan on 5/22/2016

    I am using two of these, one on a carbon reactor and the other is feeding my cpr hang on the back refugium.
  • Quiet By Robert on 3/9/2014

    The maxi-jet double pack prefilter fits on it, its about as quiet as my heater haha, i sleep close to it and can never hear it
  • Serviceable, quiet powerhead By Jeff on 5/2/2013

    I bought this powerhead for extra flow in my 18" cube coral quarantine tank. It has nearly silent operation and does its job well. I would encourage anyone looking for a small, inexpensive powerhead to give this product a try.
  • Nice pump By bruce on 4/13/2013

    The Mj400 is powering my ATO. I was very surprised how quiet the pump ran and would definitely recommend.
  • Great pump By Daniel on 8/4/2012

    I will for now on only buy Cobalt pump for my pump needs. I cant even hear this thing running and its definitely running great product.


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