Cobalt MJ Multi-Purpose Powerhead / Pump


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Notes from Penny:
This line of powerheads have been work horses for me in my reef aquariums for many years!  Way more versatile than other brands, the Cobalt MJ powerheads easily accept a 1/2" ID hose to make water changes a breeze, use to stir your saltwater but most importantly, creating just the right water flow inside your reef aquarium!  Their great price combined with longevity make this the perfect powerhead pump to use in your reef aquarium!  The second picture above is how they should look for use in your tank.  Though they come with a ton of accessories you only want to use the large intake screen & that's it!  :c)

ALSO!  Be sure to also purchase the Sure Grip Magnet Mounts for the powerheads used inside your aquariums as they will ensure they never fall!!  For more information see Sure Grip Magnet Mounts!

For my AquaCorals Reef Sytem Use:
75g to 110g - (4 ft) - (3) MJ 900 - L & R ends plus 1 back wall to front
120g to 150g (4 ft) - (3) MJ 1200 - L & R ends plus 1 back wall to front
125g to 150g (6 ft) - (2) MJ 1200 - L & R ends plus (2) MJ 900 back wall to front
180g to 265g (6 ft) - (4) MJ 1200 - L & R ends plus 2 back wall to front

Use a MJ 600 in each of your saltwater mix containers.

Cobalt Powerhead Chart

The Original MJ multi-use submersible pump and power head is built to perform and last under the harshest conditions. Ideal for wave makers, protein skimmers, calcium reactors, nano aquariums & more!


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

The MJ pump is the perfect pump for use with reactors on reef aquariums. One thing to understand is that reef aquariums have high levels of calcium, in fact at almost saturation levels, and areas with slightly higher temperatures can have active and dramatic precipitation of calcium on parts, ie impellers and impeller shafts. In as little as 4-5 months, calcium can build up enough to stop an MJ pump. Calcium build up is NOT covered by the warranty, but is easily kept in check with routine maintenance. Every 2-3 months, take out the MJ and remove the impeller, soak in distilled vinegar for 15-20 mins, then scrub parts with an old toothbrush and work the impeller up and down shaft to break up and mineral deposits. Rinse with fresh water and re-install impeller and MJ into system. This simple maintenance will keep your MJ running like new for years.

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