filters for fish bowls

Filters for fish bowls – What type to use!

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Most people start fishkeeping when they’re young with a small fish bowl or small tank in their bedroom.

Who hasn’t had a fish bowl?

Often they are gifts from people who just think you can add cold water to a bowl and drop a pretty fish in there and that’s it. It will live forever without any filtration or aeration.

Well, they are wrong!

Not only is it unfair and cruel to keep a fish in this type of environment but it isn’t very nice to have in your bedroom, the smell alone isn’t very nice.

By simply adding a small and inexpensive filter to your small tank or bowl will improve the look of the tank and make the environment better for the fish.

What’s the best option?

Buy a bigger tank would be our first suggestion, but if this is not an option then buy a small inexpensive sponge filter will do the trick.

Simply adding any form of filter for fish bowls will be beneficial to the fish and improve the experience for the person keeping the fish. This will hopefully lead them into buying a bigger tank later down the line and enjoying this hobby which we love.

Why use a sponge filter?

Fish waste contains ammonia, which is toxic to fish. In the wild this isn’t a real issue but in a small confined space the ammonia will build up to a dangerous level for the fish and will eventually kill them. 

That’s why it’s important to add a filter to fish bowls.

Sponge filters offer a gentle filtration method which is suitable for smaller fish bowls/tanks or in aquariums where small delicate fry ( Baby fish ) are present.

With larger electric pump controlled filters, they can suck smaller fish and baby fry into the unit which will kill them. Electric pumps are normally too big to go in a fishbowl anyway so a sponge filter will be the best option and sometimes the only option available to you.

They are cheap and inexpensive to run and as long as you buy a quiet air pump to run them then they are suitable for bedrooms and quiet areas.

What Are Sponge Filters?

Sponge filters like the one pictured below are exactly what the name implies, a sponge through which the aquarium water is drawn. Air passes through the middle of the sponge which causes water to be drawn through the sponge trapping dirt particles.

Once the sponge has matured which will take 2-3 weeks the bacterial which will have grown on the sponge and provide biological filtration. The bacteria will eat away at the dirt trapped within the sponge naturally. No chemicals pure natural filtration. Similar to the ocean, dirt is trapped in the sand and rocks, where bacteria eat away at the nasty ammonia and turn them into harmless CO2.

Sponges can be purchased in all sizes and shapes.  They are powered by either air pumps or powerheads which are small pumps that sit on the top of the sponge. These provide more suction which draws more water through the sponge.

Again these are normally used in larger aquariums where you don’t want the fish to be sucked up into the filtration.

The mini cylinder sponge above from Amazon will be fine and it only cost a few dollars.

What type of pump will you need?

The key to buying a suitable air pump is to buy the quietest pump which is suitable for the size of Fishbowl or Tank it’s intended for.

The last thing you want to do is buy an air pump that keeps your son or daughter up all night!

Most small air pumps will run a sponge filter in a small goldfish bowl or small fish tank.

TOP TIP: Always buy an air pump slightly bigger than it says you need. Once the sponge starts to fill up with dirt and mature it will take more power to draw water through the clogged sponge.

Don’t be tempted to clean the filter too much as this is very harmful to the bacteria growing on the sponge. It may look dirty but that’s fine, that’s what its supposed to be like.

We will talk about cleaning the sponge soon.

A three watt one outlet air pump will be fine. The FREESEA Quiet mini pump is perfect available on Amazon

What else can help in a fish bowl or small tank?

Adding Oxygenating plants to your fish bowl is also a good idea.

Plants go through photosynthesis, which converts CO2 into oxygen. So, the more plants you have in the water, the more oxygen is created.

However, you are limited with space in a fishbowl so we would still recommend the filter and air pump but they look nice and add a bit of natural substance for the fish to eat and play with.

filters for fish bowls

Egeria densa-is a good plant to oxygenate your fish bowl

Don’t rely on plants alone to oxygenate the bowl or tank. Water movement is very important in aerating the water and plants won’t do this.

A good plant to buy which is readily available in most pet stores and aquarium shops is Egeria Densa. This produces plenty of CO2 in small tanks. It’s very inexpensive and readily available in more pet store/Aquarium shops.

How to clean your sponge filter

This really is very simple and one of the best advantages of using sponge filters.

  • Take a jug of water from the bowl or tank.
  • Remove the sponge from the bowl
  • Place the sponge in the jug of water from the tank and shake and squeeze the dirt out
  • Remove as much of the dirt as possible.
  • Replace the sponge back inside the bowl

Do not be tempted to rinse the sponge in clean water, this will kill the good bacteria that’s cleaning your water.

Repeat this process every 2-3 weeks and never replace the sponge for a new one. It might look dirty but it’s doing a good job.

When you feel it’s time to replace the sponge you will need to add the new one a week or two before throwing the old one away. So for a week, you will have two sponges running in the bowl.

Split the air pump by using an air tube divider to power both sponges for one week. Then go back to a single sponge once you’re happy the new one has got enough good bacteria to keep your fish safe and clean.

Final thoughts

Try to remember what we said right back at the start of this article. If possible buy a bigger tank!

It’s not nice to keep pets in small confined space and before anyone says ‘ it’s only a goldfish and they don’t have feelings or emotions’, ask yourself, when you go near the bowl or tank does your fish come to meet you and swim to the top?

Why do you think they do that?

Because they remember who and how they get food. So if they remember that, is it possible they have feelings?

Just a thought, that’s another topic for a different day.

Fish tanks have moved on in the past few years. Technology has improved and made it easier for us all to keep fish in a clean and healthy environment. Most tanks now, even smaller ones for your bedroom have built-in lights, filters, and heaters. The one below would be perfect for a bedroom and would make a great first fish tank.

Much nicer than a goldfish bowl I’m sure you’ll agree.

Good luck and we hope you install a filter in your fishbowl no matter what type you decide on.

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