What type of filter is best for a fish tank?

What type of filter is best for a fish tank?

Aquarium filters are essential for the health of fish tanks. They are responsible for cleaning and purifying the water quality of fish tanks and providing a comfortable living environment for fish. There are many types of water filters on the market, so what filter is best for fish tanks? The following will take you to explore the three types of aquarium filters, whether RO systems are suitable for aquariums, and how to choose aquarium filters and other related issues.

What is an aquarium?

An aquarium is a container designed to keep aquatic animals and plants, usually with at least one side made of transparent glass or high-strength plastic, mainly for ornamental purposes.

It can contain anything from a simple single fish to a complex ecological simulation system, including a variety of aquatic animals and plants. Aquariums are diverse in design and function, not only providing good viewing but also with additional functions such as lighting and filtration. This type of breeding is not only a home for fish but is also often seen as part of the decoration.

What type of filter should I get for my fish tank?

Definitely. Most fish tanks almost need to use a filter. Therefore, the water filter plays a very important role in the fish tank. Without a water filter, the water quality in the fish tank may deteriorate rapidly, endangering the life of the fish. Therefore, for the fish to grow healthily in the fish tank, it is recommended to equip a water filter to provide a healthy and safe water source environment for the fish.

Should l use tap or filtered water for fish tank?

There are many options for water sources for fish farming. Among them, tap water is the most convenient and commonly used water source for fish farming. However, it should be noted that tap water may contain harmful substances such as chlorine and is not suitable for direct fish farming.

To remove these harmful substances, we can use aquarium filters to remove harmful pollutants and obtain pure filtered water. Therefore, filtered water may be more suitable.

Related:Related: Purified vs distilled vs tap water what is the difference?

What are the three types of aquarium filtration?

Physical filtration method

The physical filtration method is also called the mechanical filtration method. Its operating principle is to use filter materials with micro-pore structures to intercept solid suspended matter in circulating water so that the water quality can gradually return to clarity. It is most widely used in general aquariums.

It mainly removes solid suspended matter. It seems to be inefficient for removing soluble pollutants, especially those soluble toxic substances because such pollution sources cannot be intercepted by their pores. However, many soluble pollutants are derived from the decomposition of solid pollutants. Therefore, if most of the solid pollutants can be effectively removed, the concentration of soluble pollutants will be reduced.

The filter materials used for physical filtration are usually the filter materials we are familiar with, such as filter cotton or filter cloth. According to the sieve structure of the filter material itself and the thickness of the filter material accumulation, we can intercept solid suspended matter with particles larger than the sieve holes in the filter material, so after the filter material has been used for a long time, it is easy to hide dirt and must be replaced before it can be used again.


Biofiltration is a method that uses microorganisms to remove visible and invisible pollution. The characteristic of this method is that the filter material itself does not have the function of biological filtration at all, but the microorganisms growing on the surface of the filter material do this job. Many people do not understand the working principle of biological filtration so they cannot effectively use this method to purify water.

The visible excrement of fish (such as feces) is not toxic, but its decomposition product (ammonia) is highly toxic to fish, so it is quite threatening. Although ammonia is a gas, it is easily soluble in water, so ammonia easily accumulates in the water body, which poses the greatest potential threat to fish health.

The purpose of biological filtration is to eliminate ammonia, because ammonia dissolved in water cannot be intercepted and removed by physical filter materials at all, and can only be eliminated by nitrifying bacteria. Because the physical filter material is full of organic waste, it will inhibit the growth and reproduction of nitrifying bacteria, so it is difficult for nitrifying bacteria to survive in it and then play the role of removing ammonia.

Chemical filtration method

The main function of the chemical filtration method is to eliminate special chemical substances in water. These chemical substances are usually soluble and cannot be removed by physical filter materials. At the same time, they are mostly harmless poisons, but they may affect the color, hardness, or organic pollution index of water.

The main materials used are activated carbon or ion exchange resin. This type of filter material has a strong surface adsorption capacity or ion exchange capacity, so it can selectively eliminate or reduce the presence of certain chemical substances, thereby achieving the special purpose of improving water quality.

In normal aquariums, the chemical filtration method seems unnecessary to use. It is usually only used in certain cases for special purification purposes.

Two Main Types of Aquarium Water Filters

Although there are three types of aquarium filtration (mechanical, biological, and chemical), from the structure and working principle of the water filter itself, it is mainly divided into two types: external water filters and internal water filters.

External water filter

  • Install on the outside of the aquarium or use a portable water filter to filter the water through the filter before returning the water to the aquarium.
  • It usually contains mechanical filtration, biological filtration materials, and some models also contain chemical filtration materials.
  • Advantages: Good filtering effect, large flow, easy to clean and maintain.

Built-in water filter

  • It is installed directly inside the aquarium and is usually hidden at the back or bottom of the aquarium.
  • It usually includes mechanical and biological filtration materials, and some models also include chemical filtration materials.
  • Advantages: Beautiful, does not take up space, low noise.

The type of filter you choose depends on factors such as the size of the aquarium, species of fish, and personal preferences.

Should I choose an external water filter or a built-in one?

The type of filter you choose depends on your needs and preferences. At the same time, you can choose according to the advantages of the above external water filter and built-in water filter.

If your aquarium is larger, the density of fish is higher, and you need strong filtration, you can choose an external water filter. If your aquarium is small, and fish density is low, pay attention to aesthetics, you can choose a built-in water filter.

In addition, it is highly recommended that you use a reverse osmosis water filter, as it can remove all harmful pollutants from the water and the removal effect is very good. The most popular water filter on the market, ITEHIL Reverse Osmosis Water filter, uses PP cotton + activated carbon and RO membrane for multiple filtration, filtration efficiency of 99.9%, and a portable design with electric self-priming pump so that you can quickly get clean water.

Is the RO system suitable for aquariums?

RO reverse osmosis systems can be used in aquariums. RO systems are one of the most effective water treatment methods. It removes most impurities in the water, including heavy metals, chlorine, nitrates, etc., providing a pure water source for the aquarium. However, it also removes most minerals from the water. Therefore, if you choose to use an RO system, you only need to add a specialized aquarium mineral supplement to compensate.

Related: What Is a RO System and How Does It Work?

How to choose an aquarium filter?

Choosing a suitable aquarium filter is very important. There are many types of fish tank filters on the market. How should we choose an aquarium filter? You need to consider the following points:

Determine the volume of your aquarium

Different-sized aquariums require different levels of filtration. The filter water volume needs to match the volume of the aquarium.

Generally speaking, the amount of water circulated per hour is 3-5 times the volume of the aquarium. For example, if you have a 100-liter aquarium, you need to circulate 300-500 liters of water per hour. For example ITEHIL portable water filter.

Determine the type and number of fish you have

Different types of fish have different requirements for water quality. For example, goldfish require stronger filtration. Also, if there are too many fish in the tank, more filtration is needed.

Determine your budget

Filter prices vary greatly, and you need to choose the filter that suits you based on your budget. However, you have to consider this because many people will fall into the trap of wanting the most expensive filter, which will seriously exceed your budget.

Understanding Filtration Performance Evaluation

Filtration performance is a very important consideration when choosing a fish tank filter. Filtration performance mainly includes three aspects: physical filtration, chemical filtration, and biological filtration.

Understanding Water Pump Power and Flow

Water pump power and flow are important indicators for measuring the performance of fish tank filters. The greater the water pump power and the greater the flow rate, the better the filtration effect is usually. However, it should be noted that the greater the water pump power, the better it is. It should be selected according to the size of the fish tank and the needs of the fish.

Understand noise and energy consumption

When choosing a fish tank filter, noise, and energy consumption are also factors to consider.

Brand and after-sales

Brand and after-sales are also factors that cannot be ignored when choosing a fish tank filter. Well-known brands usually have higher product quality and a complete after-sales service system, which can provide users with a better experience.

Frequently Asked Questions

How often does the water in the aquarium change?

Under normal circumstances, if the stocking density in the fish tank is high, the power of the aquarium equipment is relatively low, in this case, the water quality environment of the fish tank is more likely to pollute and change, so the frequency of water change should also be appropriately compact, generally 5-7 days to replace 1 time. On the contrary, if the stocking density is relatively sparse, and the equipment of the aquarium works well and normally, then the water can be changed about once every 10-15 days.

How to keep the water in the aquarium clear and transparent?

Replacing the water regularly is the most basic and important step. Choose a suitable filter to remove pollutants in the water. Use a siphon to clean the bottom of the fish tank regularly to remove the deposited fish feces and other debris. Choose coarse bottom sand for easy cleaning. Add some water plants to absorb nutrients in the water, inhibit algae growth, and purify the water quality.


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