When to Change the Filter in a Fish Tank

when to change filter in fish tank

The most typical queries from first-timers are mostly related to fish tank filters. When to change the filter in your fish tank and how often? Are fish tank filters necessary at all? Which one should I use? Fear not, here is a complete guide to all your filter-related questions. 

If you are a die-hard fish lover, then the chances are that you already have a beautiful aquarium all set up in your home. You must know the routine of maintaining your tank inside and out but what about those of you who have just decided to get one?

If you want to look after pretty little freshwater or tropical fish, then you should also know everything about maintaining their surroundings, that is — the fish tank.

Do I Really Need a Fish Tank Filter?

Yes you do! Can you breathe properly in polluted, dirty air? How can your delicate fish breathe in dirty, toxic, and contaminated water? An aquarium is supposed to provide an aura of calmness and serenity, so how would a dirty fish tank look in your home or office?

The filtration system in your fish tank is necessary for the health of your fish and providing them with the proper environment. The filter not only draws in all the debris from the fish tank, but also helps beneficial bacteria grow, while moving the water continuously, so it doesn’t get that stale water smell.

Without a filter, you still can prevent the water quality to drop significantly by doing more frequent water changes. But if you do it too often, you will destroy the balance of the water itself, while frequently changing the water in your tank gets old really soon – and the larger your aquarium, the more daunting of a task it is.

That’s where a fish tank filter comes in. All you need to do is set it up and clean it instead of the whole aquarium. From a safety point of view, here is why you need a fish tank filter: 

  • To remove debris, decaying organic matter, fish waste, and excess food accumulating in the water
  • To prevent ammonia poisoning of the fish due to the presence of excess waste and toxins
  • Removal of bacteria and other dissolved organic matter
  • To keep the water clean and provide ample surface for oxygenation

When to Change My Fish Tank Filter?

And how often should you change yours is the question that pairs up well with the one above.

You see, installing a filter in the fish tank is not a permanent solution to the cleanliness problem. Your fish are constantly excreting waste into the water and it’s decomposing into ammonia. Let’s just say that you can’t run away from the task of either cleaning or changing your fish tank filter – as well as doing partial water changes as well.

Now the million-dollar question you all came here for: how often are you meant to change the filter?

Unfortunately, the answer is not very simple because many factors affect it. You can’t know for sure whether it will be in two weeks or two months that your filter will need to be changed. (But usually filters last for months or more).

This is where your observation skills and common sense come into practice. We all know that a choked filter is a useless filter. It can’t perform its functions properly if it can’t remove the toxins from the water. Subsequently, there are a few signs you can look out for which can tell you exactly when you need to change your filter. 

  • The water has become cloudy and dirty 
  • When the biological media starts to slow the flow rate noticeably
  • Your filter media is falling apart, or it seems choked

The time frame also depends on the type of filter and filtration you are using. Some fish tank filters don’t need to be changed often, while some do.

However, make sure you aren’t changing the filter unnecessarily quickly and too often. This can lead to the removal of beneficial bacteria in the water. It is better to read the recommendations given in the instruction manual of your tank’s filtration system.

And remember: in most cases, you don’t have to change the filter, but clean it. Rinse it well in the water that you have removed from the tank (or at least use dechlorinated water, or else you will destroy the beneficial bacteria living there).

How to Install a New Filter

Before installing a new filter, you must know about the type of filtration method being used in the aquarium and it usually depends on two major factors: whether you have an external filter, or an internal one (with a sponge)

For instance, you can change the mechanical portion of the filter whenever you like. But when it comes to chemical or biological filters, the filter can be changed once the filtering process has occurred.

The key to changing your fish tank filter is to make sure that you don’t lose the beneficial bacteria in the process. The following are some easy ways of installing a new fish tank filter without losing the bacteria:

  • Leave your old filter media with the new one for about a month for the cultivation of bacteria
  • Put the old filter’s media into the new filter, which is of the same size and shape to prevent the loss of bacteria
  • Colonize the new filter by simply putting the old filter’s media next to the new filter for about a month if you can run two filters
  • If it is a sponge, simply place it in the tank’s water for a week or two, so that the beneficial bacteria colonize it.

Now you know everything you need to know about when to change filter in fish tank to keep all your finned friends happy and healthy! But if you have additional questions, don’t hesitate to ask them below.

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