Do The Cure All Aquarium Carbon Cubes Actually Work?

In Aquatic Rambles 2 comments

These miraculous cubes showed up on the aquatic western market in 2017. They were marketed to the west as a cure-all for everything aquarium related, absorbs nitrites, nitrates and ammonia, clear green water in a matter of hours, absorbs residue medications, removed smells and my favourite, it can kill fish diseases and eliminate water changes for up to 6-12 months. 

So how did these magic aquarium cure-all cubes come about?

Well, this may be a shocker to some but the activated carbon cube was never intended for aquarium use. The product was originally used for wardrobes to help keep clothes smelling fresh in humid environments in southeast China.

A few local aquarists started using them in their aquariums, and their ability to polish water rather efficiently began trending on fish groups on Weibo (Chinese social media).

Eventually, a few aquatic companies took notice of the trend and started boxing up the carbon cubes for aquarium use. However, it was Guangdong trading company that introduced them to the western market through the likes of Aliexpress and Wish.

If you have read my other posts, you will know I think trading companies are a curse on the hobby. They have no knowledge of aquatics and will sell whatever they can by any means possible to make a profit. 

In this case, they marketed the cube as a solution to all our aquarium problems. 

Tired of water changes? ... No problem, add a cube. 

Got sick fish? Add the cube. 

Too much algae and green water? Cube! 

Fortunately, some aquarists in the hobby saw through their nonsense, but a lot did not, especially newcomers.


The cubes are made from activated carbon nothing more and nothing less. Activated carbon works like a big magnet absorbing molecules of pollutants, gases and liquids, clumping them together on its surface. This remarkable occurrence is considered a physical phenomenon is also known as the Van Der Wall Force.

The carbon cube certainly would make a good alternative to the old school granule carbon, as its matrix design would have a larger surface area allowing it to trap more pollutants. 

However, like all carbons, it would eventually exhaust itself and release the trap molecules back into the aquarium. So, to keep the carbon cube in the aquarium for up to 6 -12 months would be detrimental. Fortunately, as of late, trustworthy brands that sell the cube are marketing it responsibly, without all the added nonsense.  

In my opinion, they are a gimmick but at the same time, I cannot deny their efficiency as a carbon product. For daily use, the carbon cube does nothing more than what a dollar bag of standard activated carbon would do. Nevertheless, the cube does do it marginally quicker due to its large surface area. 

At the end of the day it all comes down to your budget, the carbon cubes can cost up to 12 dollars, so if you run a lot of tanks you are going to be on your second mortgage quicker than you think. 

For us at Castle Dawn Aquatics, carbon is something that needs to be changed regularly and maybe that is old school thinking, but for us, we will be sticking to good old carbon granules for the foreseeable future.

If you are still considering buying a carbon cube, do NOT leave it in your aquarium for 6- 12 months, and if you are insisting on reusing it, take it out at least once a month and give it a good wash in freshwater. 

This product can not replace a good water change, and it certainly will not cure fish diseases, as so many have advertised in the past.  

Use our Amazon affiliate link below to get your Magic Cure-All Cube:


Disclaimer:  I hope some of you found this article interesting or at least killed 5 minutes on your bus journey to work. As always, the articles I write are based on my experiences and knowledge of working in the aquatic industry for well over a decade.

This article is not intended to offend, trigger or oppose anyone's personal opinions or experiences.


2 thoughts on “Do The Cure All Aquarium Carbon Cubes Actually Work?

Christopher Morris

These things are ridiculous, I see people all the time asking about them on Facebook, anyone who is looking for something to eliminate water changes should not be keeping an aquarium in my opinion. Like your writing style, you cut through the bull s**t.

February 3, 2022 at 15:54pm
Adam Karel

I was looking to buy this and came across your article on google, it is listed on Amazon that it will eliminate water changes for up to a year, figured it would be handy when away on holidays, but I will not waste my money.

May 25, 2021 at 22:10pm

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