Sparky: the $3 Micro Fish Tank Filter





Introduction: Sparky: the $3 Micro Fish Tank Filter

Meet Sparky, a micro filter for fish tanks that only costs $3. It is so simple to make and it is the perfect size for a betta tank or another small aquarium. If you want to use it with a larger tank, you can just double up!

Why do you need a Filter?

A filter is absolutely essential for any fish tank! Not only does it help remove harmful toxins from the water such as nitrite and ammonia, but it also provides a colony of beneficial bacteria essential for prime fish health.

Why is Sparky a Great Filter

Sparky not only provides mechanical filtration (from the sponge) but also provides biological filtration from the biohome media, combining the two most crucial elements of filtration. Not only is this unusual for such a small filter of only 5cm long, but it is virtually unheard of!

Step 1: Supplies

You will need:

  • A scouring sponge: if you have an old sponge at home you can peel off the scouring part (rinse it first!) and use that or you can pick up a sponge at the dollar store. Make sure it hasn't been treated with anti-fungal or anything at all for that matter. If you want to spend a little extra you can use an aquarium sponge.
  • A piece of biohome mini ultra (or ultimate) filter media (or other): you can get a free sample of biohome filter media from their website. It is by far the best choice. You can use a ceramic media put it just won't work as well. With biohome it can be broken into smaller pieces and adapted to your container size.
  • A container: I used a small little container that came with a USB cord and was the perfect size. They were popular little contraptions about 3 years ago and were used to hold two ferrite core halves to help stop electrical interference. If you can't find one of those you can modify one of those travel sized soap bottles or, even better, a film canister holder by drilling a hole in the cap for the airline and holes all around the body of the bottle.
  • A drill and small drill bit (optional)

You will also need an aquarium air pump and some airline.If you don't already own one (most fishkeepers do) then you can buy a very cheap one that gets the job done for $5.

Step 2: Cutting Your Sponge

Cut out two squares that are the width and length of your container from the scouring sponge. Gently tuck them in the two halves. If you are using a travel sized bottle or other, wrap the sponges along the inside of the bottle.

Also cut out a circular sponge the size of the base, put it to the side.

Step 3: Biohome Media

Put your piece of media in between the two sponges. Before shutting the container, put the circular sponge you cut out inside, so it covers the bottom. Now close up your container and make sure that it is firmly shut.

Step 4: Optional Modifications

You need to drill some small holes on the body of your filter to enhance water circulation if it doesn't already have holes. My container already had holes, so I only made a few extras.

Also, I found a suction cup in my spare parts drawer that I hot glued to the bottom of the filter. This made sure that it stuck to the bottom of the tank when it was in use.

Step 5: Attach Your Airline

Attach an airline to the hole at the top of your filter, push it about 7/8 down the body and you are ready to give it a spin. It was that easy, and your fish are going to love it!

How does it Work?

The airline and air pump pump air into the body of the filter. This sucks water through the sponge and piece of filter media, triggering a siphoning action. Air bubbles will then escape, along with your filtered water out of the holes in the body.

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Cool Instruct.

Great and clear...!

What's the website for the biohome media...?

1 reply it's an excellent product that I support 100%

If you want an extra addition ask about the biohome "ultimate". It's the same as the one I used, but it also contains trace elements.

Very interesting idea, and a great first instructable!

Have you done any comparative testing to see how well this works versus traditional filters? I'd be curious to see how it did!

2 replies

I'm glad you enjoyed reading it! It is a traditional idea in a non-traditional form, if that makes sense. With small filters generally they are only filtered via a sponge, and are therefore not very effective, while with larger, traditional filters they have the addition of biological elements. My idea combines the larger filter concept of two-stage filtration in a micro size.

Very cool idea. Thank you for the explanation!

Does anybody have some of that biohome media? I tried emailing the company website but they said they didn't give out samples like the instructable says.

I'm going to make one of these. Would it work to use an airstone for the biohome media? i already have one of those, and if it just stuck it in the center of the sponge...?

Nice work. I see some major design flaw, though. With the air flowing into the body and thus creating a pressure zone inside the body, I don't think there will be an effective water circulation through the sponges. The construction will most probably work as an air diffusor of sorts, which is a good thing also in a fish tank, so no downside here.

7 replies

I have to agree here, I really don't see how this device creates any kind of 'siphoning action' This would work no better to filter the water than a standard aquarium air pump using a difuser stone at the end of it.

I see why you might be questioning. The filtration/siphoning action is similar to that of your standard sponge filter. Air goes in and rises up, and while it rises it pulls water up with it, so water is pulled through the sponge and biohome media. It's difficult to get your head around at first, but it honestly is a pretty simple concept.

I agree. Anyone who has kept a fishtank with sponge filter or that ugly "corner filter" will understand the concept :)

But this is so small that the only kind of tank you can put this would be a small betta tank and bettas don't need air circulation at all. So where would you put it?

My boyfriend used to have a jar with only few shrimps and slugs inside. It was a vary small version of an aquarium (3 litres if I remember well) and this super tiny filter would have been perfect for something like this.

Even though everyone says bettas don't need a filter, in my opinion EVERY fish needs a filter. People also keep bettas in tiny jugs when they need at least 5 gallons.

As well as bettas this can be used for small community tanks (1 for a 5 gallon, or use 2 for a 10 gal) and shrimp tanks.

I agree with you on air circulation, but betta's really only need a gallon. I've had many bettas that have all lived long lives even by betta standards and they've all been in tanks 1-2 gallons in size.

For me it has worked very efficiently. I think the best way to do it is to push the airline about 7/8 down the body, thus eliminating any pressure. I will make this clearer.

Coming from the view of an experienced fishkeeper I say go with a cheap product that will last you a decent amount of time. If you have to power multiple things with it then use one with 2 or more outputs. Mine is a Tetra Whisper, affordable and good quality.

I've used the foam from hair curlers as a sponge filter in film canisters and other similar containers with good results. The biohome media is new for me and I'm anxious to try it out!

Just an FYI as stated in some of the comments, aquariums should only contain natural things, like rocks, plants, gravel and sand. Filter medium should always be brand new, clean and from an aquarium store. You can clean an aquarium with water and salt (any kind of plain salt), if you are using rocks, driftwood etc. that you have collected yourself you should definitely boil them for about 10 minutes in a container/pot that has never been used, or alternatively you can soak them in water with bleach and then rinse thoroughly until there isn't even a trace of bleach odor. Gravel from a store should be rinsed as well and rocks IMHO should be boiled too.