Do I Need a Filter for My Fish Tank?

When I was new to fishkeeping, I often wondered whether I needed a fish tank. I may not have had the answers back then, but by now, I know.

So, if today someone were to ask me:

Do I need a filter for my fish tank?

Not necessarily. Technically you don’t need a filter for your fish tank to work properly, but it would be really hard to maintain a proper level of biological filtration without using a filter. For instance, you will have to change the water every single day, regularly clean the tank, and you will also be limited in the choice of fish you can keep.

Got your answer? Great! But wait, there’s more. Did you know that plants can help you get rid of a filter altogether? If you didn’t, then stick around because I have a lot more to share.

Need for Fish Tank Filtration (Video)

A Filter Is Not Necessary, but You May Want to Get One!

To explain why you don’t need a filter, but you may want to get one, we first need to understand what a filter is. So, to put it plainly:

A filter is a device that aids in the biological filtration.

And what is biological filtration? It is a natural process that goes on inside a fish tank in which waste materials like Ammonia, Nitrates, and Phosphates are filtered. By filtered, I mean they get consumed by the plants. Plants use these waste materials as nutrients, undergo photosynthesis, and in return, produce oxygen. Fish breathe this dissolved oxygen, and the cycle repeats itself.

Biological filtration aids in maintaining a sensitive balance. If this balance gets disturbed, it could result in the degradation of the whole ecosystem.

And this is exactly where filters make their strongest arguments. See, most of the time, people don’t have enough plants to support the biological filtration. This leads to several problems.

Some of them are:

  • Frequent water changes are necessary to sustain the ecosystem in such a situation
  • Reduced amount of dissolved oxygen
  • Fish may not grow properly and may show diminished activity levels
  • Accelerated algae growth
  • Waste buildup in the tank

All of the above problems are fatal to fish. To get rid of these problems, you have two options:

  1. Increase the number of plants in the fish tank
  2. Install a filter

The second option is more practical, in my opinion. You install a filter once, clean it at regular intervals, and you are good to go.

Now bear this in mind:

A filter is nice, but it is not necessary.

If you have a good mix of plants and if you regularly clean the filter, the tank and change the water, you can get by without having to use a filter.

Why You Need a Filter?

A filter aids in biological filtration and ultimately helps sustain the ecosystem inside the tank.

If you are still unsure as to how a filter helps in sustaining an ecosystem, here is how:

Filters Increase the Amount of Dissolved Oxygen

Yes, you read that right. One of the most important things that a filter does is increase the amount of dissolved oxygen. You see, filters create ripples or currents on the surface of the water. These currents result in the surface of the water getting agitating, which promotes increased oxygen dissolution.

The more the dissolved oxygen, the healthier the overall ecosystem. A healthy ecosystem is responsible for the well-being of your fish. Studies suggest that fish thrive in an environment with more oxygen. They become more active and grow much better.

Filters Get Rid of Waste Materials

Fish produce a lot of waste. This waste includes Ammonia, Nitrates, Nitrites, and Phosphates among other things. It is important for an ecosystem to get rid of this waste if it is to function properly. Biological filtration helps in getting rid of the waste substances. And you know what helps the biological filtration? A filter.

So, here’s the deal:

When you use a filter, it aids in biological filtration to reduce the waste substances into consumable nutrients for plants.

Not only does this reduce the waste, it also promotes plant growth and inhibits algae growth.

Good Bacteria Love Filters

The thing is:

Not all bacteria are bad.

No matter the ecosystem, bacteria play a vital role in maintaining a critical balance. These microorganisms break down complex chemical substances into simpler ones so that plants can consume them. This is essentially what biological filtration is.

So, bacteria are good, and an ecosystem should have as many as possible. And filters provide a pretty good habitat for them to grow in.

Now you know why you might need a filter.

Do All Fish Need a Filter?

The short answer is:

No, not all fish need a filter.

But there is much more to this subject than meets the eye.

First of all, you need to understand that not all fish live in the same type of habitat. Some fish come from ponds, some from rivers while others may be from the ocean. Each type of fish will have a different set of requirements when it comes to building a habitat for them.

Some fish can live without a filter, while others need a filter. Some need heating while others don’t. This pattern continues for other requirements as well. So, no matter the type, be sure to research before making any final decisions.

Some of the more common fish who don’t need a filter are:

  • Bettas don’t need a filter to live in a fish tank. This is because Bettas have the ability to breathe oxygen from the atmosphere in addition to the dissolved. This ability allows Bettas to survive on a minimal amount of dissolved oxygen
  • White Clouds are relatively small fish. They don’t need an abundance to live. This also includes the amount of dissolved oxygen. White Clouds only need a few gallons of water to thrive, so a filter is not necessary
  • Goldfish is, perhaps, the most well-known of the fish mentioned here. Goldfish can live in a tank and won’t even require a filter. Smaller Goldfish can survive for longer periods of time without a filter as compared to big ones

While it is perfectly feasible to keep fish in a tank without a filter, it is far from the ideal. Your first priority as a fishkeeper is to look after the well-being of your fish. And the more healthy their environment, the better your fish will be.

Types of Filters

There are two basic types of filters:

  1. External Filters
  2. Internal Filters

External Filters

External filters are just that, external. These filters are kept outside of the tank. They operate by drawing the water in, filtering it, and then releasing the water back into the tank. External filters are easier to operate. They have a high initial cost, but they make up for it with smooth and trouble-free filtration.

There are a few different types of external filters:

  • Canister Filters are shaped like a can. Since these filters are external, they are kept outside of the tank. The thing that differentiates these filters is their ability to carry multiple filtration media. These filters are known for their quiet and efficient operation, but these can be quite expensive.
  • HOB Filters can be thought of like a miniaturized version of Canister Filters. They work on the same principles as the Canister Filter but are smaller and more affordable. They also work by drawing up water, filtering it, and then pumping it back in.

Internal Filters

Internal Filters, as the name implies, are placed inside the tank. These filters are often cheaper and smaller as compared to external filters. They are great if you don’t have a lot of room outside the tank. But as always, they also make compromises in a few areas.

Following are the different types of internal filters:

  • Sponge Filters are placed inside the tank. They are submerged in the water. They draw in water through the use of a water pump, pass it through a sponge for filtration and release it back in. These filters are small, cheap and are easy to maintain.
  • Undergravel Filters are placed under the gravel. These filters are quite effective against waste buildup in the substrate and are pretty easy to maintain.

While both external and internal filters can be used to filter the water, they both have their disadvantages.

For external filters, disadvantages include:

  • Expensive
  • Difficult to maintain

For internal filters, the disadvantages are:

  • Take up space inside the tank
  • Undergravel filters are bad for aquatic plants because these filters oxygenate the essential nutrients consumed by plants

The key to choosing the right type of filtration is to consider your particular setup.

Maintenance of Filters

Just like all the other equipment, filters need regular maintenance. Regular maintenance ensures that the filter is operating optimally. Smooth and optimal operation equals effective waste management, which leads to healthier fish and an overall healthier environment.

External Filters

External filters are quite easy to maintain. Because an external filter is placed outside the tank, you just need to disassemble it, wash the filter media with the tank water, clean the insides with a cloth, and assemble it back together.

A word of caution:

Don’t wash the medium with tap water or anything other than the tank water. Doing so will kill the bacteria that have grown on the medium. And you wouldn’t want that to happen.

Internal Filters

Internal filters follow much of the same pattern as external filters. The only difference lies in its placement. It is ideal that you clean an internal filter when you are changing the water. For instance, you place undergravel filters under the substrate, so they require regular cleaning. Clean these filters every week for optimal performance.

Finally, when it comes to filters, the more you look after them, the better they will perform. To put it plainly, clean them regularly, and if you see a failing part, change it as soon as possible.

Frequently Asked Questions

The following are some frequently asked questions that you should take a look at.

How long can my fish tank go without a filter?

Most beneficial bacteria start to run out of oxygen after about 30 minutes. Fish follows a similar pattern. So, your fish can go without a filter for a few hours. But don’t think your fish can go over a day without a filter especially if there aren’t that many plants in the tank.

As you can see, there is no clear cut answer to this. Fish and beneficial bacteria both depend on dissolved oxygen. Since a filter is responsible for oxygenating the water, when there is no filter, there is no more oxygen. While some fish like the Goldfish can live without a filter, most fish will start feeling the effects of deoxygenation.

Can you turn off a fish tank pump at night?

Yes, you can but only for a few hours. If you keep the pump turned off for more than a few hours at a time, the fish will start feeling the effects of deoxygenated water. Not only your fish but the beneficial bacteria growing in the tank will also start dying after about 30 minutes due to the lack of oxygen.

An air pump is crucial for maintaining a healthy level of oxygen in the water. Turning it off will negatively affect the overall ecosystem of the tank. In short, you can turn the pump off at night but be careful regarding the duration.

Are fish tank heaters safe?

Fish tank heaters are safe. Most fish tank heaters are made from materials that have been tested against short-circuit and any other potential causes of failure. So, you don’t need to worry about safety issues. However, there are some other things that you need to ponder.

One of the things is the type of fish you keep. Do some research and find out if your fish is a cold-water or a hot-water fish. If it is a cold-water fish, don’t use a heater as it will be degradative to your fish’s health. For fish other than cold-water, you are good to go.

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