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Cobalt Aquatics MJ Water Pump Multi-Purpose Powerhead (5W/7.5W/8.5W/20W)

4.4 out of 5 stars 363

Currently unavailable.
We don't know when or if this item will be back in stock.
MJ600 (7.5W | 160 GPH)
Brand Cobalt Aquatics
Color Black
Material cotton
Style Submersible
Power Source Corded Electric
Item Weight 0.9 Pounds
Maximum Flow Rate 605 Liters Per Hour

About this item

  • Uniquely durable. The mj’s impeller uses a high-strength nylon infused fin-system that flexes to prevent sand, dirt, pebbles, etc. From damaging the fins and pump. Includes 3-year warranty.
  • Extremely quiet and reliable. Made in Italy (same as original maxi-jet) and the quality of manufacturing is evident from the moment you turn it on. Cobalt’s MJ is one of the most reliable and quietest pumps on the market.
  • Secure mounting. Triple Suction Cup mount ensures the MJ stays in place.
  • Fully rotational and customizable for many uses. See product images for all the many MJ power head/pump Accessories and uses. Includes 6 foot power cord and cord guide
  • Selection guide. See the product images to determine the best MJ size for your tank.

Customer ratings by feature

Suction power
4.4 4.4
Value for money
4.2 4.2

Product details

  • Is Discontinued By Manufacturer ‏ : ‎ No
  • Product Dimensions ‏ : ‎ 2.75 x 4 x 8 inches; 14.4 ounces
  • Item model number ‏ : ‎ 30001
  • Date First Available ‏ : ‎ August 23, 2011
  • Manufacturer ‏ : ‎ TopDawg Pet Supply
  • ASIN ‏ : ‎ B005QRH57I
  • Customer Reviews:
    4.4 out of 5 stars 363

Looking for specific info?

Product Description

The Cobalt original MJ multi-use submersible and external pump and power head is built to last under the harshest conditions. Ideal for protein skimmers, wave makers, calcium reactors, nano aquariums, under gravel filters, terrariums and hydroponic applications. Made in Italy.

Important information

Directions

Ideal for wave makers, protein skimmers, calcium reactors, nano aquariums, under gravel filters and hydroponic applications.

Customer reviews

4.4 out of 5 stars
4.4 out of 5
363 global ratings

Customers say

Customers like the quality, noise, performance, value, and flow of the water pump. For example, they mention it's well built, works great for the job, and is quiet in operation. Some appreciate the flow rate, saying it moves a lot of water quickly.

AI-generated from the text of customer reviews

114 customers mention107 positive7 negative

Customers are satisfied with the quality of the water pump. They mention it's a well-built, reliable powerhead that is quiet and powerful. Some say that the fit and finish of all attachments are more solid. Overall, customers are happy with their purchase and recommend it to others.

"...This is a great, well-built pump that is a good fit as a replacement for the Biocube 29g stock pump...just don't expect a huge increase in tank flow..." Read more

"...Other than that, the pump seems to be well built and I would expect it to last for a long time." Read more

"...The product is very quiet, sturdy, and well made, much better then the Maxijet. This is Made In Italy, while the Marineland Maxijet is Made in China...." Read more

"...They operate less noisy than other brands, are very reliable, and have good head pressure..." Read more

108 customers mention83 positive25 negative

Customers like the noise of the water pump. They say it's extremely quiet in operation, and generates minimal heat. Some say that the MJ900 has a dramatic reduction in noise compared to the original.

"...It runs very quiet and seems to run at the same temperature or slightly lower than the stock pump...." Read more

"...There is a dramatic reduction in pump related noise coming from the MJ900 vs. the original Coralife S-700 even though the MJ900 moves 27% more water..." Read more

"...The product is very quiet, sturdy, and well made, much better then the Maxijet. This is Made In Italy, while the Marineland Maxijet is Made in China...." Read more

"...That was 10+ years ago. They operate less noisy than other brands, are very reliable, and have good head pressure..." Read more

72 customers mention61 positive11 negative

Customers like the performance of the water pump. They say it works great for the job, is the best working powerhead they've found, and is really happy with its performance. Some mention that the pump seems powerful and has good output. Overall, most are satisfied with the performance and recommend it to others.

"...It has good output as well, so ultimately this is a GREAT pump for the 29g Biocube...." Read more

"...I bought this pump to use with my water chiller, and it has been working great!..." Read more

"...I ended up connecting #7 to #2 and it works great. It's just a little shorter than I'd like. They still deserve a 5 starts...." Read more

"...I use mine to suck water through a big Eheim sponge pre-filter. Works like a charm..." Read more

35 customers mention26 positive9 negative

Customers like the value of the water pump. They say it's well worth the money, a reliable pump for the price, and a great purchase. Some customers also mention that it works well for the money and is worth the wait.

"...Would I use one for a sump pump in a basement - no. But a good reasonably price makes them hard to beat.I just ordered a couple more...." Read more

"...So far, worth every penny" Read more

"...Fortunately this was able to work.. unfortunately this is extremely expensive for this size of a pump..." Read more

"...Powerful, and more importantly, silent. Well worth the few extra dollars. Go ahead, spoil yourself with this first-class power head/Pump." Read more

28 customers mention28 positive0 negative

Customers are satisfied with the flow of the water pump. They mention it provides a strong water flow, it's quiet, and it moves a lot of water quickly. Some say that it'll increase the flow inside their aquarium. Overall, most are happy with their purchase and recommend it to others.

"Has a very great flow, I love this pump because it is very universal and you could use it for quite a number of things...." Read more

"...Perfect amount of flow. Very versatile with an adjustable outlet angle. A very nice accessory kit comes with it and it's very quiet...." Read more

"...While the MJ600 provides fairly reasonable water movement for their size, I do wish I'd have gotten a slightly larger version...." Read more

"...The circulation also helps move detritus to the filter intakes. My favorite feature of this powerhead is the venturi...." Read more

14 customers mention14 positive0 negative

Customers like the accessories that come with the water pump. They mention that it runs completely silent, has several accessories options, and comes with all the accessories you will need for multiple settings. Some appreciate the mounting pieces and customization parts. Overall, customers are happy with the accessories included with the product.

"...Very versatile with an adjustable outlet angle. A very nice accessory kit comes with it and it's very quiet...." Read more

"...heat unlike some other powerheads, and there are enough fittings and attachments in the box that one can set these up in just about any..." Read more

"...This one was exactly what I expected. it comes with a lot of mounting pieces that I do not understand...." Read more

"...TO SAY THE LEAST THEY ARE SIMPLE AND VERY WELL BUILT. THEY COME WITH ALL THE ACCESSORIES YOU WILL NEED FOR MULTI SITUATIONS BEYOND USING THEM AS..." Read more

11 customers mention8 positive3 negative

Customers find the installation of the water pump to be easy. They mention that it's simple and well built. Some say that the pump does not come with instructions.

"...the third chamber where the stock pump resides, so I had no issues getting it installed...." Read more

"I PURCHASED TWO OF THESE PUMPS IN JULY 2012. TO SAY THE LEAST THEY ARE SIMPLE AND VERY WELL BUILT...." Read more

"...Easy to maintain. Don't short cut to save $$$. The others will never last the same or they will rattle." Read more

"...I just used the mounting bracket and suction cups. there are no instructions of how to use the other mounting pieces...." Read more

13 customers mention8 positive5 negative

Customers are mixed about the size of the water pump. Some mention it fits perfectly in their skimmer box, and is a good fit as a replacement for the Biocube 29g stock pump. However, others say that it is way too large for this application in a small tank, the hoses don't fit, and the parts don''t cross fit.

"...This is a great, well-built pump that is a good fit as a replacement for the Biocube 29g stock pump...just don't expect a huge increase in tank flow..." Read more

"...it as an extra flow pump in the display area, but it is way too large for this application in such a small tank...." Read more

"...All pieces fit together well. The only big difference is the propeller shaft is metal, not plastic...." Read more

"...Superb fit and finish to all the pieces, would recommend." Read more

Absolutely worth the money!
5 Stars
Absolutely worth the money!
UPDATE: Three years of 24/7 use and still running like a champ!I bought this powerhead April 2015 and ran it in a 20 gallon goldfish tank on this DIY filter with a 100 ml carbon bag under the media. It pulled water through a biosponge, the carbon bag, and the Biohome media for a year without a hitch. The only problem was that the flow was not strong enough to generate aeration (certainly NOT the Cobalts fault since it was me that put so many hinders des in its way).Three months ago I moved it to my 55gal, took out the carbon bag and put the aeration tube back on. It's still running like a champ. We have hard water so I take it apart every 2-3 weeks and get rid of any lime deposits.It's very quiet in an in-tank set up without the bubbler. It's a little noisy with the bubbler tube on it but no more so than a good sized air stone and pump would be. I highly recommend this powerhead. I have a less than spectacular Fluval C4 running in the same tank that has been a bit of a pain. I'm thinking of ditching it and building a second DIY filter powered by another Cobalt workhorse. It would certainly give me less trouble, be easier to clean, and not require purchasing replacement pre filters and carbon bags!
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Top reviews from other countries

Jeff
5.0 out of 5 stars Silent and reliable
Reviewed in Canada on November 28, 2017
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D P S
1.0 out of 5 stars Product had not worked since very first day. We ...
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Alveus
5.0 out of 5 stars Works well
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computerdad2
4.0 out of 5 stars Nice pump for the application.
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TH
5.0 out of 5 stars Very quiet pump works well with 29 gallon biocube
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