How Long Can A Fish Filter Stay Off – Will Your Fish Survive? – Water Purification Guide_water purifier industrial fallout 76

2022-08-13 12:14:17
How Long Can A Fish Filter Stay Off – Will Your Fish Survive?Written by Russell Singleton in Fish,Pets,Pond,Uncategorized

Your fish filter is very important in keeping your fish tank clean, keeping your fish healthy, and maintaining oxygen levels. There are different reasons why you may need to turn the filter off, such as cleaning. But how long you can leave the filter off without harming your fish?

A fish filter can be switched off for 8-10 hours in a day, and for up to three days. The number of hours varies based on tank size, species of fish, and the fish population. Fish filters are engineered to run 24 hours a day, seven days of the week, and it is not advisable to leave your fish filter off unnecessarily.

In this article, we discuss how long you can leave the filter off for a selected species of fish and the effect of leaving it off for a prolonged time. We also discuss certain conditions where you may need to turn off the fish filter and how to navigate those situations.

Factors that affect how long to leave a fish filter off

1. Tank size

Tank size affects the amount of space that your fish has to swim around and interact with its environment. In general, thelarger the tank size, the longer you can leave the fish filter off.

For example, if you have a huge tank with small-sized fish in a small number, you would be able to leave your filter off for a maximum of three days.

This is because the rate of waste production, oxygen consumption, and toxin accumulation would be relatively low. 

2. Number of fish

This is almost similar to the tank size factor.

The larger the population of fish in your tank, the shorter the time you can leave the fish filter off.

Metabolic activities will be high for a large population, and so will the waste deposits. You need a filter continuously running to clear out these wastes as quickly as they’re generated.

3. Fish population species

There are hundreds of fish species that are reared in a fish tank. They differ in terms of maintenance requirements, feed, life expectancy and adaptability.

Unless you’re certain that all your fish species will do well without a filter, do not leave the fish filter off for more than an hour. One hour is the estimated time for replacement or cleaning of filters.

4. Tank maintenance

One of the benefits of a fish filter is that it removes debris from the tank. If you decide to turn off your filter, you must be ready to constantly clean out the tank by changing the water or through other means.

The longer you can manually maintain a clean fish tank, the longer you may be able to leave your filter off.

Note that your fish behavior is very critical in making this decision. If the fish species are not tolerant to stress, do not opt for manual water changes.

Other factors

This includes the presence of tank plants known for oxygen supply and toxin absorption. Also, the manual introduction of useful bacteria at least twice a year to complement activities of the plants can affect how long you can leave the filter off. 

The principle here is to make sure that even without a tank filter, there are other conditions or actions put in place to adequately substitute the known benefits of filters.

The longer you can maintain those conditions, the longer you may be able to run your fish tank without a filter.

What happens if you turn your fish filter off for a long time?

A fish filter helps bacteria to break down toxic chemicals into safe byproducts. It also removes debris, dead plants, waste products, and uneaten food from the tank.

If you turn off your fish filter for a long time, you will be subjecting your fish to any of the following conditions:

1. Deoxygenation

Your fish, plants and some useful bacteria in your tank require oxygen to thrive. A fish filter ensures that there’s adequate oxygen supply in the tank.

So if you turn it off for a long time, these organisms will have difficulty surviving and may eventually die.

2. Algal build-up

When you leave the fish filter off for a long time, algal growth increases exponentially. This is due to imbalance of nutrients and gases, which provides conducive conditions for algae species to establish. 

Contaminated water due to debris and algal build-up can also be an attractant for snails and other water-borne pests. These organisms are a threat to the fish population in your tank, in terms of health and the resources available.

3. Loss of beneficial bacteria

Aquarium filters are responsible for regulating the microorganism population of your fish tank.

These organisms play an essential role in maintaining a healthy tank environment by removing toxins from waste products. If you turn off your fish filter for a long time, the toxins can cause the microorganism population to die and lead to serious health issues in the fish population.

4. Ammonia and nitrate build-up

Ammonia is a byproduct of fish waste and is a very toxic chemical in fish tanks.

The beneficial bacteria from the filter in your fish tank are responsible for breaking down this toxin and preserving your fish health. They perform the detoxification with the help of oxygen which is supplied by the fish tank filter. 

If you turn off your fish filter for a long time, the aerobic bacteria will die from lack of oxygen. Then, the ammonia generated from fish waste will build-up and poison your fish, eventually causing their death.

Benefits of leaving your fish filter on at all times

Leaving your fish filter to run continuously has the following benefits for your fish:

Beneficial bacteria:

Your fish tank needs bacteria to keep the environmental conditions at optimum level. Without a filter, the bacteria will not survive and irregularities in the water condition could affect the health of your fish.

Temperature regulation:

A constantly running filter helps the water heater to control changes in water temperature. If you have species of fish that are sensitive to temperature change, leaving your filter on at all times will protect the fish from stress and premature death.

Water agitation and movement:

This is especially important for optimum gas exchange in the fish environment. Carbon dioxide and oxygen are released and introduced into the water, which helps the survival of your fish, plants and other habitants of the tank.

Tank maintenance:

Fish tank filters are responsible for clearing out inorganic and organic debris materials from the tank. Without filters, your tank will be full of debris that would release unpleasant odors to your home.

Reasons to turn off a fish filter

Noisy filter:

You may want to turn your fish filter off because the noise it makes prevents you from having a sound sleep.

Instead of this, there are other ways to reduce the noise from the filter. Filter noise is caused by insufficient water in the tank, accumulated dirt in the filter which affects the impeller and filter tubes, or an unsuitable flow rate.

Instead of turning off your fish filter to manage the noise, you can:

  • Increase the water level in the tank so that the filter is immersed and the noise is reduced,
  • Adjust the water flow rate in the tank until the noise is barely above a whisper, 
  • Disassemble the filter and clean out debris or mineral deposits from every part based on your user’s manual, or
  • Change the filter completely and replace it with a quieter one

Energy consumption:

Maintaining an aquarium consumes a lot of energy.

From the aquarium lighting and heater to the pumps and filters. The lighting and heater consume 80% of the total energy your aquarium uses.

This implies that compared to the lighting and heater, fish tank filters consume an insignificant amount of energy, from as little as 3 Watts to as much as 50 Watts per day, depending on tank size and filter type. 

To conserve energy, consider using a lighting bulb that is energy efficient, reducing the heating temperature by a degree or two, and adjusting the rate of gallons of water pumped per hour.

Your fish tank filter is unarguably the most vital part of your aquarium. If you want to conserve energy, turning off your filter is not the effective way to go.

Filter cleaning or changing:

A dirty or damaged filter will do more harm than good to your fish tank. Cleaning or replacing the filter requires turning off the filter for about half an hour, which is not harmful to your fish or the beneficial bacteria.

It is advisable that you clean your filter either weekly or at two to four week intervals, depending on the manufacturer’s instructions. You should also replace your filter as soon as you notice that it’s not operating optimally, or as recommended by the manufacturer.

Power outages:

In some cases, a power outage is unavoidable and uncontrollable.

The survival of your fish during this period will depend on the duration of the outage, the fish species, and the condition of the water in the tank before the outage.

If you experience power outages that last for days and your fish species are those that need a filter to survive, you could consider getting a power generator for such situations.

However, if you have some cold water fish species like the guppy and Betta fish, you have nothing to worry about during a power outage. All you need to do is frequently change the tank water to prevent toxin poisoning.


Going on a vacation or a work trip is not a reason to switch off your fish filter.

As long as your aquarium is running, the filter should also be running. You can get a family member or a close friend to turn it off for a few hours intermittently, but ideally, your filter should run all day.

How long can a pond filter be turned off for?

Ponds that contain fish should have a dedicated filtration system that can run continuously. Ponds are at a greater risk of algal build-up than other fish housing systems. 

Small populations of small-sized fish can survive for days without a filter. However, if you have lots of goldfish or a Koi fish and you turn off your filter, they may only have 4-5 hoursof air before they start dying. 

If you have pond plants, an air pump, and can supply essential bacteria to your pond at intervals as well as change the water, your pond filter can be left off for short periods of time. 

Will fish in a filterless pond last longer than fish in a filterless tank?

The fish species directly affects its survival in certain conditions.

However, in general fish in a pond without a filter are more likely to die quicker than fish in a tank without a filter.

This is because a pond is more susceptible to algal growth and toxin build-up, especially if it doesn’t have pond plants.

Should you turn off your fish filter every night?

A fish filter should run continuously, and not be switched off at night. If necessary, a fish filter can be switched off for a few hours at night, but not every night and not for an extended period of time. The tank size, fish type and population size will affect how long a filter can be switched off before negatively affecting the fish.

How long can fish survive without a filter?

The type of fish you have will have a large impact on how long you can leave your fish filter off for.

Below are estimates of how long the most popular types of fish will survive without a filter. However, bear in mind that the maturity of the fish, size of the fish population and tank size will influence these timeframes.

FishSurvival timeframe
Angelfish12 hours
Goldfish12-48 hours
Mollies12-48 hours
Plecos2 hours
Tetras12 hours
White Cloud Mountain Minnow24 hours

How long can Angelfish go without a filter?

With ample tank space and a moderate population, angelfish will live for up to 12 hours without a filter.

However, overcrowding will cause angelfish to die prematurely.

How long can a Betta fish go without a filter?

Betta fish will survive fordays, weeks, and possibly monthswithout an aquarium filter, as long as you perform frequent water changes.

However, if you do not adhere to proper maintenance requirements, your Betta fish may not have much time to live. 

You should know that the frequent water changes for a long time may stress your Betta out, leading to sickness and then death. 

How long can goldfish go without a filter?

Goldfish can survive for 12-48 hourswithout a filter to supply oxygen and reduce chemical build-up before it dies ,. Goldfish need oxygen as well as enough water flow and tank space to survive. If the tank is big and it has enough space to occasionally get oxygen from the surface, then it could last longer than a few hours.

How long can Guppies go without a filter?

Guppies can survive 2 days to 1 week without a filter. Although, this will depend on the size of the guppy population and tank size. As long as you can keep the environment healthy, guppies will live without a filter for a long time.

How long can Plecos go without a filter?

Bristlenose plecos and other pleco species produce a lot of bio-load. Without a filter for oxygenation, water agitation, and waste removal, your pleco fish will not survive longer than 2 hours, especially if it’s a very mature or large fish.

If you have to turn off the filter in a tank holding plecos, use an air pump to supply oxygen, and change the water every 24 hours.

How long can Mollies go without a filter?

Mollies can survive for12-48 hourswithout a filter. Factors like the age of the fish and water quality will affect the timeframe.

How long can Tetras go without a filter?

You can leave Tetras in the tank without filters for around 12 hours as they do not mind if there’s no water filtration system running. However, you should turn it back on after that period has passed since green algae will start developing and cause dangerous levels of nitrates that might kill these fish if left untreated. 

You should also provide them with a healthy environment to keep them alive even when there are times where the filter is turned off.

How long can White Cloud Mountain Minnow go without a filter?

The White Cloud Mountain Minnow, or WCMM, is a part of the Cyprinid family, making them active fish that require more oxygen and activity. It can survive up to 24 hours if you turn off your filter. But, make sure it turns on again after this period has passed since green algae will start developing due to a lack of water filtration system running in their tank.

In an ideal environment, the WCMM can survive without any filters, but if you cannot maintain the tank daily, then a filter is a must, and you should only turn it off within the recommended time. 


Will my fish die if I turn off the filter?

Fish will not die if the filter is turned off for short periods of time. However, if you turn off the filter frequently or for an extended period of time, your fish may die. This is because the fish filter plays a huge role in oxygen supply and tank maintenance, which are crucial for the survival of your fish.

Will my fish be OK without a filter for a day?

Some fish can survive without a filter running for an entire day. The survival of the fish will depend on whether the environment is clean, there is enough oxygen, and the population is moderate.

Now, if you have different species of fish in your tank, and the rate of fecal production is relatively high per day, or the amount of abandoned food is high, then your fish may not be okay without a filter for a day.

However, if the fish population is low and the water level and quality is high enough, your fish will be okay without a filter for a day. As a temporary substitute for the fish tank filter, and to ensure oxygenation, you can use an air stone that will generate bubbles and supply oxygen. 

A damaged filter or power outage could make your fish tank stand for a whole day without a filter, but make sure to turn it on as soon as you can to avoid damages. You can also complete regular partial water changes to supply the fish with oxygenated water.

Does a fish tank filter need to be on at all times?

A fish tank filter should be on at all times. A continuously running fish tank filter will ensure your fish is getting all the oxygen it needs, and that it is living in a clean and healthy environment.

How long can fish survive without a filter?

Without a filter, the range of survival for fish is from 3 to 48 hours. However, this depends on the species of fish and the size of both the tank and fish population. Some aquarium fish species can survive without a filter, but they usually require the most care and maintenance. They are cold water species and need their water changed frequently to avoid toxin poison.

Some examples of fish species that may not require a filter are: Betta fish, guppy fish, Ember Tetras, Scarlett fish, Zebra fish, and Pea Puffer fish.

You can read more about fish that don’t need a filter in this great post.

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