We are reader supported. When you purchase through links on our site, we may earn an affiliate commission. Also, as an Amazon affiliate, we earn from qualifying purchases.
As most people should know, having a filter in a fish tank is vital for the health of your fish. Without one, your fish can become quite sick. Fish tank filters can be quite power hungry and noisy, though. A lot of people wonder whether they are able to turn their fish tank filter off for short periods of time because of this. Let our experts answer that for you.
So, how long do you leave the filter on in a fish tank? Well, all the time. Filters should never be switched off. The second the filter is switched off is the second that the water will start to get rather filthy for your fish.
We do want to expand upon this a little bit, as well as give you some information on how often you should be replacing the filter on your tank. This will help to ensure that you keep your fish as happy and healthy as possible.
How Long Do You Leave the Filter on in a Fish Tank?
You should never turn that filter off. It really is as simple as that.
It doesn’t matter how noisy or irritating the sound of the filter starts to get, if you switch it off, you are putting the health of your fish at risk.
What you need to remember is that fish produce a lot of waste. In the wild, this is not a problem. They have huge amounts of water to swim through, and that water will dilute the waste to the point where it doesn’t really harm the animals living in the water.
Fish tanks are different. They are enclosed spaces of not all that much water. If you do not have a filter in your tank, then any waste produced in your fish tank is just going to stay floating around in the water. This may be fish feces. It may be moldy food. It could be plants, etc. It may even be things that have fall in from outside of the fish tank.
Without a filter in place, all of that waste is just going to be floating there in the water. This waste is going to be producing bacteria, etc. Your fish is going to be ingesting it. This can result in them becoming sick, and sometimes even dying.
The job of the filter is to keep that fish tank clean. It is meant to stop all of that filth from starting to gather in the tank.
Once that filter is turned off, that water is no longer circulating. The fish are still going to be producing waste, but none of that waste is going to be removed from the water. While you may be able to get away with the filter not working in the tank for a couple of hours, anything longer than that, and you are sure to be running into a problem or two.
Basically, never turn that filter off. Make sure that it is constantly running. If the filter manages to turn itself off for any reason, then you need to fix the problem. If that filter is off for more than a couple of hours, then your fish are in danger.
How Often Should You Replace a Filter in a Fish Tank?
It depends on the filter that you own. Of course, you won’t be replacing the entire filter, but the filter media. This is what grabs all that dirt and grime when the water passes through it.
In most cases, you should be replacing the filter media in a fish tank every 3-4 weeks. This is what most manufacturers recommend, at least. We certainly wouldn’t recommend having your filter media attempting to filter the water for anything longer than that.
However, there may be times where you will need to replace the filter on the fish tank far more often. If your fish tanks are crowded, they are going to be producing a lot of waste. The filter may not be able to keep up. Make sure that you replace the filter media often.
If you notice that the water is starting to become a little bit murky, or your fish are acting somewhat lethargic then, once again, you are going to want to be replacing that filter media a little bit earlier.
What Size Fish Tank Filter Should You Buy?
When you are looking for a fish tank filter, you will very quickly notice that all of them have a number called ‘gallons per hour’ (GPH). This is the amount of water that the fish tank filter is able to filter through for each hour that it is turned on. This number is vital information.
The biggest mistake that people often make is selecting a fish tank filter that has a GPH number that is the exact same size as their fish tank. Don’t do this. It would mean that the water in your tank is only being cycled through once per hour. It is important that you choose a GPH that is at least 4x larger than your fish tank. For example, if you have a fish tank that is 20-gallons, then you will need a fish tank filter that is more than capable of handling 80-gallons of water per hour it is turned on.
Do you need a filter in your fish tank?
Yes. You always need a filter. Without a filter, there is no way to remove the waste from the fish tank. This can eventually result in your fish becoming sick, or even dying.
What is the quietest fish filter?
Both AquaClear and XpertMatic fish filters are touted as some of the quietest fish tank filters around. Most of the fish tank filters that have been rated for quietness will say so in the marketing material. If they list a dB, then you want that dB to be as low as possible. It is impossible to get a completely silent fish tank filter.