When we talk about filtration in fishkeeping, people often say that the third step is chemical filtration.
But do you really need chemical filtration in your aquarium?
Below, I will explain when you might use chemical filtration and if it is truly necessary.
What is chemical filtration?
It is one of the types of filtration we can use in an aquarium. I’d like to highlight the words “we can use.”
The types of filtration that are truly necessary are biological and mechanical filtration. Although, to be honest, only biological filtration is truly essential.
Mechanical filtration is mainly needed for us, the fishkeepers, to keep the water in the aquarium clear and visually appealing.
Surprisingly, it is not necessary for your fish and plants to stay healthy. In the wild, water is not as clear as in our aquariums, and this actually benefits the fish, such as by allowing them to hide from predators.
While biological and mechanical filtration have their roles, chemical filtration serves entirely different functions. As the name suggests, chemical filtration is meant to remove various chemicals from your aquarium.
As I mentioned earlier, the purpose of chemical filtration is to remove all chemical substances present in your aquarium. This includes substances like heavy metals, compounds such as sodium chloride, medications used to treat fish, or tannins from wood.
Some chemical media can even remove small amounts of ammonia or phosphates, which contribute to algae growth.
Since we want to maintain clear water in our aquarium, we can use certain chemical media to achieve the best visual effect.
Now, let’s get to the heart of the matter…
Do you need chemical filtration in your filter?
The short answer is: No!
Yes, earlier I explained how chemical filtration can be used and acknowledged that it serves some purpose, without a doubt.
But do you really need chemical filtration in your filter? No.
Are you sure I don’t need chemical filtration? Absolutely not.
And I’ll repeat it once more: No!
You might feel a bit confused now, but let me explain why. In any well-maintained aquarium that is regularly cared for, there is absolutely no need for chemical filtration.
If someone tries to convince you that it is essential, they are simply wrong; it is a tactic aimed at profit.
Let’s not fool ourselves – this has been a marketing gimmick in the hobby for decades, suggesting there is a third stage of filtration.
As I mentioned earlier, the only truly essential filtration in an aquarium is biological filtration. If the right bacteria develop in your filter, trust me, they will do their job, and your aquarium will be healthy.
The whole story began with activated carbon. And, of course, I’ll emphasize that it does have its functions in an aquarium, but, as I said, it is not necessary for a healthy aquarium.
Don’t be fooled into thinking you need replacement cartridges with activated carbon or other chemical media to clean your water. This will only cost you money without solving the root cause of your problem.
There is no real research that shows chemical filtration is necessary for an aquarium to function properly. There are studies showing that biological filtration is essential, but there is no such evidence for chemical filtration.
While chemical media won’t harm your fish, using them is often unnecessary, and they are not as effective as they may seem. I have used chemical media myself, and I might use them again, but it is important to have the right knowledge about when and why to use them.
What is the best type of chemical filtration?
Below, I will explain which type of chemical filtration is the best. However, it’s important to note that there is really no such thing as the “best” chemical filtration.
Each filtration medium serves a different purpose, and it depends on the specific situation in which you want to use it.
As I mentioned earlier, if there is truly no need to use chemical media, then simply don’t buy them, as it would be a waste of money.
However, if you feel they might help in your situation, it is always worth trying.
I have also spent a lot of money on various filtration media — some were more effective, others less so.
However, the most important thing is to maintain biological balance from the very beginning. This way, your aquarium should not face any problems.
So, let’s take a closer look at the most popular chemical filtration materials.
Activated Carbon
I’m sure this name sounds familiar to you. You’ve probably heard of it in many cosmetic advertisements.
Activated carbon has been used in fishkeeping for many years. One reason for its popularity is that it deals with a wide range of impurities and is easily available and inexpensive.
Its price means that, in reality, you aren’t throwing money away; it offers more benefits than drawbacks.
Each piece of activated carbon is designed with tiny pores, which are small holes too small to see with the naked eye. These pores are what capture all the impurities from the water.
Activated carbon is used for the following purposes:
- Removing brown tannins that leach from certain types of decorative wood
- Removing odors from aquariums with poor aeration
- Removing medication residues, but only malachite green and methylene blue
- Removing food coloring from fish food
- Removing chlorine and chloramine, but very slowly — so slowly that it cannot quickly remove high concentrations of chlorine, which can be dangerous for fish
I want to emphasize that activated carbon does not remove any toxins, heavy metals, or other harmful substances.
You may often come across claims that it removes heavy metals, but this is simply not true, as it does not have this ability.
I write more about activated carbon in a separate article.
MarineLand Diamond Media Premium Activated Carbon, Blacks & Grays, 40-Ounce (PA0373)
Zeolite
Natural zeolite is mainly composed of silica and aluminum. In fishkeeping, we usually encounter synthetic zeolite, which is man-made.
However, this is not a significant issue since it functions almost identically to its natural counterpart.
Like activated carbon, zeolite also has many tiny pores, but it works differently. The main purpose of zeolite is to remove ammonia from the water.
Zeolite absorbs ammonia and exchanges it for sodium, a process called ion exchange. This process continues as long as the zeolite has sodium to exchange.
It has also been proven that zeolite can reduce ammonia levels even in marine environments, although it is not as effective as it is in freshwater.
I should note that, although I have used zeolite myself, I believe a well-functioning biological filter will remove ammonia more effectively than using zeolite.
You may also hear claims that zeolite clears the water. It’s hard to confirm this. I’ve used zeolite in many of my aquariums and haven’t noticed any dramatic change.
It seems to me that other factors have a more significant impact on water clarity.
You might also come across mixtures of zeolite and activated carbon.
Marineland White Diamond 50 Ounces, Removes Toxic Ammonia, aquarium Filter Media
Oxide (Phosphate Remover)
Aluminum oxide and iron oxide can effectively reduce the phosphorus levels in an aquarium, which can help solve algae problems.
However, it’s important to note that some materials can increase the level of aluminum in a saltwater aquarium. Therefore, saltwater aquarists should prefer using iron oxide.
Using granules that remove phosphates is recommended because high phosphate levels can cause algae blooms.
In most cases, cyanobacteria blooms are due to high phosphate concentrations in the water.
If a 90% water change does not remove the phosphates, the best solution would be to use the appropriate granules.
Seachem PhosGuard, 100 mL bagged – 67101850
Ion-Exchange Resins
Resins are commonly used for softening and purifying water, so it’s no surprise they are also used in fishkeeping. Resins work similarly to zeolite, using ion exchange.
However, they can remove far more impurities than zeolite.
Synthetic resins are generally produced to target specific chemical waste, such as phosphates, nitrates, or heavy metals.
They are typically used to treat water during water changes and to adjust aquarium water to remove nitrates or ammonia.
However, I have not found any information confirming that resins remove heavy metals.
For this type of chemical medium, a media bag is needed, as the resin consists of hundreds of tiny particles.
Without a media bag, these particles could easily escape into the aquarium, making the filtration less effective.
Fluval ClearMax Phosphate Remover, Chemical Filter Media for Aquariums, 100-gram Nylon Bags, 3-Pack, A1348, All Breed Sizes
A warning before installing your chemical filter
However, you must remember that using chemical media when they are not needed can do more harm than good.
Additionally, chemical filtration media do not last indefinitely. No matter which type of filter you use, there will come a time when it simply become full.
When that happens, the filter will no longer serve its purpose and won’t absorb impurities from your water.
Instead, a saturated chemical filter can release those trapped impurities back into the aquarium.
This defeats the purpose of using it, so it’s important to know that chemical filters need to be replaced regularly.
How long a particular chemical filter lasts depends on many factors. Some may work for about two weeks, while others may last for a month.
Usually, the manufacturer specifies on the packaging how long a filtration medium will remain effective.
However, I believe you should focus on removing the root cause of the pollution in your aquarium. Using chemical media should only be a short-term solution.
Not only will you spend money, but you also won’t solve the underlying problem.
If there is no need for a chemical filter, then don’t buy one. The only one I think is worth considering is a phosphate remover, which is generally effective and, with the right care, can help you get rid of algae.
Of course, always read the instructions to know how often to replace the chemical filter.
In conclusion
As you have read in this article, I believe that chemical filtration media should only be used as a last resort.
Of course, there’s nothing wrong with using them since they are available on the market.
I think it’s important to look at this from different perspectives, not just from the idea that manufacturers are trying to make money off of us.
Some filtration media are more effective than others, but it’s important to find the right balance.
If there are filtration media that simply do not work, then don’t buy them. However, if there are media that might help, it’s always worth giving them a try.
This experience will help you make better decisions in the future.
Do you use a chemical filter in your aquarium? If you have anything to add to the discussion, feel free to share it in the comments!
