Can You Use BBQ Charcoal for Aquariums?

Many types of aquarium filters do a good job of cleaning all the toxins, waste, and contaminants from the water.  One of the oldest water purifiers known to man has been charcoal, and over the years, it has been used for hundreds of different purposes.

New tank owners may read that charcoal possesses these properties, but it can leave many wondering which kind of charcoal they can use. One of the easiest types of charcoal to lay your hands on is the one you use on your outdoor grill. It looks the same, so, is it possible?

Can you use BBQ charcoal for aquariums? The charcoal you get for the BBQ can be broken up and added to your aquarium filter, yet it isn’t something you should contemplate doing. While it looks the same as the charcoal you get for aquariums, it is very different.

The charcoal you use in aquariums is known as activated carbon. The manufacturing process differs, and the result is very different. Read on, and you can see the differences between the two, and why activated carbon is the one you need to use in your aquarium.

Why is BBQ Charcoal Different to Activated Carbon?

BBQ charcoal is not the same as activated carbon, and it does come with additives to help it burn and perform the way it does. The manufacturers add compounds such as Borax, Nitrate, and Lime during the manufacturing process.

To a certain degree, both are manufactured in the same manner, yet activated carbon, or as it is also known, activated charcoal is pure by the end of the manufacturing process. If you added a BBQ brick to water, after a while, there would be an oily film forming, which is the fire-starting chemicals they are treated with.

One other difference during manufacturing is the size of the particles. BBQ briquettes are made to be dense. Once lit, they burn slowly; however, activated carbon is ground into a fine form that delivers a much larger surface area. Additionally, these small particles contain tiny pores, and it is these which trap all the waste, and toxic elements from the water.

What Else is Activated Carbon Used For?

All of the tiny pores will trap pollutants as your tank water passes through this portion of your water filter. In many cases, it can be used to remove the following:

  • Fish medications
  • Phenols that lead to pungent smells
  • Water discoloring tannins
  • Chlorine and chloramines

You may be using this if you have an RO (reverse osmosis) filter for your home or the water you use in your aquarium. This form of carbon does a fantastic job of clearing water and removing any smells. It is for this reason; you see it in insoles for shoes to remove foot odor.

Nowadays, many aquarium filters come with activated carbon as part of the filtration system. If your filter doesn’t have one, you can easily add it to your existing filter system.

The one thing with using activated carbon as part of your filter, it doesn’t last too long. Once all the pores are full, then it needs changing. You can tell this because you can start to smell again as the filter becomes ineffective.

This can be done as part of a regular maintenance routine and isn’t too costly because activated carbon can be cost-effective.

How Long Will an Activated Carbon Filter Last?

If you care for your tank, and the water conditions are quite good, then an activated carbon filter will last longer. If your water is dirty, then it will require changing sooner. A good guide is that they will last around one month for regular aquariums.

To be sure it lasts as long as possible, it does need placing after any mechanical filter you have in your system. This way, you are certain it won’t be blocked by larger debris.

One good thing with using activated carbon is that once it is full, it hangs onto everything it traps and won’t let these leech back into your aquarium. If you miss changing the filter for a few days, there is no need to worry that it will affect your tank.

What Can’t Activated Carbon Do?

Activated carbon is very effective, yet it isn’t a solution to everything, and should never be seen as a one-stop solution for tank cleaning.

There are some things it can’t remove, and these include:

  • Nitrates
  • Nitrites
  • Ammonia

To control these, you still need to carry out your water changes and keep an eye on the nitrogen cycle.

Other things this carbon can’t remove are heavy metals. Iron is one, and if your water source does contain this, you need to remove this beforehand.

There are many places, which may lay claim to you being able to reactivate carbon. This, in reality, isn’t possible and is a pointless exercise. Other individuals may claim you can rinse the particles. Once again, this isn’t true.

Once activated carbon pores are full of contaminants, they remain full, and you can toss the filter into the trash, or add the carbon particles to a compost heap.

Activated Carbon Types

There are several kinds of activated carbon available, although you will only be using one kind in your aquarium.

They make each type for specific uses.

  • BAC – Bead Activated Carbon
  • EAC – Extruded Activated Carbon
  • GAC – Granular Activated Carbon
  • PAC – Powdered Activation Carbon

The one for use in aquariums is the GAC (Granular Activated Carbon) variety.

In days gone by, these compounds were made from wood. Nowadays, there are different materials that manufacturers use to make both charcoal and activated carbon.

  • Wood
  • Coconuts
  • Peat
  • Bituminous coal

The material you will be looking for is the activated carbon that comes from Bituminous coal. While you can use the other forms, this type has a few advantages over the others.

The pore structure is the crucial part of activated carbon, and the pores in this variety are far superior to the other three compounds. The other thing that makes it special is it has been designed with water purification as the primary use. Any water treatment filters or machines in homes will have this kind of activated carbon as the main component.

If you see any for sale in pet stores or aquarium shops, be sure to check. Others may be cheaper, yet they are inferior and clog much quicker while removing fewer pollutants. If you have a freshwater tank, make sure to check for activated carbon, which contains phosphates. This will leach into your tank, and it will spark a massive algae outbreak.

Fish on Medication and Activated Carbon

One thing to be wary of is that activated carbon is very effective. If you have sick fish and add medication to your tank, the filter will remove this from the water. Not only will your fish not receive the medication, but also you will be spending money on something that isn’t being used.

You will need to remove all traces of carbon from your tank before you use any medication. Once you have finished the medication of your fish, all it takes is to add your activated carbon back, and the traces of the drug will clear from the water.

How Much Carbon to Use

The amount to use will depend on the kind of filter you have. Newer models may have sections where you can slot a filter inside when you change them.

If you need to measure, then the general rule is around 2 cups of activated carbon for 55 gallons of water. You can calculate this to the size of your tank. While this figure is a starting point, it isn’t set, and you can use more or less, as you think, is necessary.

Aside from smelling coming from the top of your tank when the filter is full, you may notice a slight yellowing of your tank water.

Some models of filters contain slots where you add your different kinds of filters. In some cases, they may not use them all, and you can use the empty one to add your activated carbon. The way to do this is to purchase an aquarium filter mesh bag. These are highly affordable, and all you need to do is fill these with your carbon and give it a rinse to make sure there won’t be any dust floating around your tank.

Slip it into one of the slots, and your water will begin being cleaned. The advantage of this instead of purchasing activated carbon filters, is you can save money in the end. One mesh bag will last for years, and a jar of activated carbon is cost-effective.

Activated Carbon Precautions

Here are a few things to pay attention to if you decide to use activated carbon:

  • Coconut Based Carbon: Carbon made from coconuts has its uses; however, it is a bad choice for aquariums. It produces a microporous carbon that isn’t suitable for fish tanks.
  • Planted Tanks: If you have many live plants in your tank, you may need to reduce the use of your carbon as it can remove some of the trace elements your plants need.
  • Loose Carbon: if you find there are a couple of pieces of carbon floating around in your tank, there is no need to worry. These won’t affect your tank, though if you can scoop them up, then do so.


The use of activated carbon, in most cases, won’t hurt your tank. However, many enthusiasts don’t consider its use as being too much of a benefit to their aquariums. It is a personal choice to use it or not, and it is cheap enough so, you can test it to see if it offers your tank and your fish anything different.

It isn’t a solution, that can eliminate water changes, and doing this regularly can be sufficient in many instances.

The main thing is that you should never consider BBQ charcoal as an equivalent, no matter who says it can be used.

Do this at your peril because you can end up with a tank that takes a considerable amount of cleaning, and the possibility of dead fish.