Introduction: Cheap Homemade Aquarium Filter

Picture of Cheap Homemade Aquarium Filter

Aquarium filters are expensive, especially the replacement filters. Using things I had laying around the house, I made some of my own for under $.25.

Step 1: Commercial Filters

Picture of Commercial Filters

Commercial filters are expensive (unless they came with your tank at a garage sale, like mine).

Step 2: A Filter's a Filter...

Picture of A Filter's a Filter...

I realized how simplistic those commercial replacement filters are, and found a substitute: air filters.

Now, these commercial filters come with carbon or other media as a chemical filter, so I just bought my own.

Step 3: Create a Pocket...

Picture of Create a Pocket...

Create a pocket for the chemical media. I simply hot-glued the edges.
Be sure to squish the glue between the filter parts.

Step 4: Fill With Chemical Filter Media

Picture of Fill With Chemical Filter Media

Now, prior to just making my own filters, I did use commercial filter replacements without the plastic frame that comes molded to them (I don't know why there was no plastic frame; I got them free). However, those puffed up with use.

I recommend putting a staple in the center of your new filter to keep it from puffing up like that.

Add chemical filter media.

Step 5: There You Have 'er.

Picture of There You Have 'er.

Insert filter.

This has been my first instructable. Give me criticism.



Micuti (author)2014-08-27

Like the idea. How's about cheesecloth that's used in making cheese and straining fine liquids from foods. It can be bought at any grocery store for about a dollar and is safer. It can be cut to size and fitted in the plastic brackets. I plan on using it for our tank. Will let you know how it works.

becksta29 (author)Micuti2016-05-11

good idea,did it work?

smokey4u (author)becksta292017-01-24

I had to replace my waterbed mattress. Being it was waveless . The fiber fill in it will be enough to keep me in 12" x 12" filters for my near 600 gallon Koi pond. Tho it does clog up in 2 weeks and not something you'd want to even try to rinse out. Thank goodness I have a boat load.

Ata akbar (author)2016-03-23

very useful idea

Brockfiger (author)2016-03-13

Good idea and good follow up from everyone. ty

elmer.nickerson.5 (author)2015-03-14

When I used the frame + bag cartridges I always put the bag in a jar of hot water and shook it until it was clean, that kept it from getting flattened and worn out by other means of washing it. You can use bleach if you like them white. One box of cartridges lasted me several years. Now I just get a sponge and cut it to fit the filter. Rinse it under the tap when it gets full and never worry about it again.

Micuti (author)2014-08-27

Oh. You can also pull the pads and the plastic brackets out and run them in your dishwasher's rinse cycle on hot. The jets will flush all the yucky stuff out.
Have fun.

xtacsoulja (author)2009-11-05

The staple is not going to cause any problems at all, I have been using staples to secure plants to driftwood for several years and have had no ill effects, it takes a lot non-collated iron to be piosonous, but anyway great idea and a good instructable

The part I would worry about is the vent material. Some contain fiberglass and other not-so-good things for your fish. More importantly, a lot of the vent filters today are anti-bacterial and you want bacteria in your filter medium, that's why you rinse it out in aquarium water, so you don't destroy the bacteria.

I like your instructable a lot, but I think it might be safer if polyester batting were used instead.

dgbiles (author)phoenixfire0892014-01-30

What about a couple of coffee filters?

thebriguy (author)xtacsoulja2010-04-15

if anyone is worried about the staple i think a dab of hot glue on the center would also keep it from puffing up.

Ptyochromis (author)2014-01-29

Why don't you use the big rolls of un-cut filter pads? They cost about $8 for a 12x8" sheet.

infernisdiem (author)2013-05-04

I have been using the same filter pads in my tank for about 3 years now, all I do is pull out the pads, hit them with hot water in my sink, and stick them back in, never had an issue with pH jumping around, or high level so of nitrates/nitrites, though aquarium salt might have had something to do with that lol

DrewBrew (author)2008-10-30

Great idea! I'm tired of buying filters. I've been prolonging the life of store bought filters (ie Whisper Bio-Bags) by dumping out the old charcoal, removing the filter from the plastic frame and rinsing the filter under the faucet while gently scrubbing with an old toothbrush. I would then replace the filter and add fresh charcoal (purchased from pet store). Much cheaper than using a new Bio-Bag each time. Your tip will save me even more cash by making the filters from scratch. The info about charcoal being useless is also good to know. I always thought that the charcoal played a big part in the filtration process.

pyroarchist (author)DrewBrew2011-03-20

for future reference,
i wouldn't clean the actual filter body, as that will have beneficial bacteria on it, acting as a biological filter, keeping ammonia and nitrite levels down.

iwade4fish (author)DrewBrew2009-08-05

Good economizing! But in the future, refrain from using tap water if you are unsure of its hypochlorite (chlorine, bleach) levels. The chlorine removes the beneficial bacteria from your filter material. One option is to reserve a small amount of the aquarium water in a container and rinse, or slosh, your filter in the container. Not as thorough of a job, but the benifit to the water, and your fish, is worth it.
Made a diy wet-dry.

popomaster (author)iwade4fish2010-01-02

well, a good aquarium setup should have at least 2 small filters if your aquarium is around 10-20 gallons. alternate replacing each cartridge every few weeks and the beneficial bacteria will remain. larger aquariums usually already have filters that have 2 filter ports but smaller filters usually dont due to there bulky nature

Scott_Tx (author)2008-10-09

Dont forget that you can re-activate carbon by baking it

dreadly (author)Scott_Tx2009-05-16

This is a myth, it has to be heated to over 400degree to work.

pyroarchist (author)dreadly2011-03-20

my oven goes to like 850... what are you trying to say?

dreadly (author)dreadly2009-05-16

I think you have to sit back and reflect on just exactly what "Activated" carbon is, and what it does or is supposed to do - and how it does it.

Activated carbon is an adsorbent and, as such, adsorbs selective impurities on its physical, external surface. It does this by a type of Van de Waals attraction that requires a certain degree of energy to liberate and dispel the captured contaminant molecules and return the parent activated carbon back to its state of “activation”. However – and this is a BIG however – the regeneration of the adsorbent is only effective to the degree that enough energy is supplied to dispel most – never “all” of the captured contaminants. In other words, the effective level of “activation” decreases with succeeding regenerations, until a relatively stable, operational activation level is reached. The effective adsorption level of the carbon depends on the heat energy level (temperature) supplied and its duration (total energy supplied). The higher the temperature, the better the degree of regeneration – as long as the energy duration is sufficient to dispel most of the captured impurities.

With regards to activated carbon, the usual regeneration temperatures recommended are in the range above 300 – 350 oF. Anything less than these temperatures has to be labeled as “token” regeneration and not really taken seriously. But that depends on the quantity and the type of impurities captured on the carbon. Some molecules are easier to dispel than others. If you are talking about microscopic quantities of odor molecules, then you might succeed in regenerating a percentage of the spent activated carbon by using a clothes dryer at a temperature of 250 oF. However, the resultant regenerated product will not have the expected full adsorption capacity. You are going to have to accept a reduction in its future effectiveness if its regeneration is not going to follow the regeneration temperature specifications.

What I have described is essentially what happens in an industrial adsorption unit – such as a Molecular Sieve dryer. If you do not regenerate the Mol Sieve with a temperature of around 500 – 600 oF, you should not expect to obtain an ultra-low dew point product (like 0.5 PPM vol. water content). The higher the regeneration temperature, the more thorough the regeneration and the more efficient the adsorption action of the adsorbent in the next subsequent operation.

Brainchigger1 (author)dreadly2009-08-05

deadly, Will a microwave oven do it ???????????

popomaster (author)Brainchigger12010-01-02

microwaves work by heating tiny water particles in the food. thats why when you microwave some foods they get chewy or dry because the water molecules tend to evaporate or collect. Dont know honestly how much water is in carbon so you might as well try a hobo stove. they get pretty hot and if your good at camping easy to start. Little mess too.

abbyy (author)Scott_Tx2009-02-03

Interesting... Do you know the temp. and time it takes to bake it?

Scott_Tx (author)abbyy2009-02-03

really not sure, just something I've heard. I'd check google for info

Mr. Smart Kid (author)Scott_Tx2009-03-03

i think i read some where like at least 1000-3000`

blizz86 (author)Mr. Smart Kid2009-04-01

thats way too high, melting metal at that point.. there is no point in re-activated carbon, its pretty cheap when bought in bulk and is only useful if the tank is extremely dirty or stinky.. or when you need to take medicine out of the water..

Sgt.Waffles (author)Scott_Tx2008-10-19

Does not work.

ausisit (author)2010-06-03

After reading much about it and the many uses for activated carbon and the care thereof. We steam with an iron or small steam cleaner like a Pullman Jet Steam  to clean and reactivate, then bake our activated carbon.  This works just fine for many of the uses.

dafrimpster (author)2010-03-04

Quilkt batting is much cheaper than the register filters you are using. I have been making my own replacement filter bags from it for years. I get a year's worth of filter material for about 6bucks. I use it in my canister filters as well. Good and very cheap!!

jimmiek (author)2009-08-23

I'm not so sure that the rust will kill the fish, after all, we use rusty nails in the Aquaponics system if we can't find Chelated Iron for the plants. I'd give it a spin with some cheap Goldies, or Guppies, if it won't kill a Goldie, it's OK .... carp are susceptible to just about everything - I lost 45 of them over time just trying to raise them for aquaponics. Rusty nails works OK with Tilapia (Cichlidae). This is a great instructable .... one I will definitely use, since my way of not buying these expensive filter cartridges didn't work out so well !

steed1172 (author)2009-05-25

you said give you criticism.. but this isn't really that. what about the rest of the filter? the part that takes up water.

dreadly (author)2009-05-08

Great :) I would recommend NOT putting a staple in though, it will rust and release non collated iron. This is poisonous to freshwater fish and inverts as i understand. Another small dab of glue would be much better idea I think.

bwpatton1 (author)2009-04-30

Those air filters are SOO usefull, I am using one on a home-made air filter in my room right now.

bassmonkey (author)2009-04-27

you an reuse the one's in my ten gallon, you just replace the carbon, yours isn;t like that???

Tony G (author)2009-03-22

Will the hot glue affect the fish in any way once it is dry and in the filter?

miguelg4u2 (author)Tony G2009-04-18

No, i will be like plastic in a fish tank. It will be fine.

unhg (author)2009-04-15

Did the same thing, except I sew it together instead of glueing (more safer for my fishies).

CrystalStranger (author)2009-01-07

Or you could reuse the plastic cage from the old filter after cleaning it- I used to do that regularly when I bought the ones without the plastic.

mjarthur (author)2008-12-10

one point... the Glue gun, it can have nasty chemicals in that glue, most aquarium glue has to be of a certain type so it wont leach into the water and kill your fish... p.s. i have a fresh water tank and i just rinse out my filters, maybe occasionally changing the carbon in them if i have some sitting around, i find that if you aerate enough the bacteria can do their work without harming the fish

profquatermass (author)2008-10-29

You do know that the reason manufacturers put a pocket of Carbon in tank filters is that it's a hang-over from the 1970s when people had lead or copper tap water pipes and so there were dangerous chemicals in their water.


These days, this is not true (for the most part). Activated Carbon (AC) works fairly quickly and within 3 days it'll have done its work so can be removed. So unless your tap water is full of heavy metals you don't need to use it.

Manufacturers don't like to tell you that it is 95% used up within 3 days. They tell you to remove it after 2-3 weeks! (Well they've got to make you feel that you've gotten your money's worth haven't they?)

AC removes chlorine from water but you should really be removing this via a water conditioner liquid as it works virtually instantly. AC will take that little bit longer and your fish will be exposed to toxic chlorine.
Of course these days a lot of tap water suppliers put Chloramine in it. This is not removable with AC. So the use of AC is almost obsolete these days.

It's also not great for plants as the AC absorbs elements that plants need like Iron.

Why do the filter makers still supply it? Because it's a nice little money earner...
has the details.

PKM (author)2008-10-09

Criticism: image notes are a helpful device, especially when parts of your images may be hard to understand, but your photos are clear and your instructions are good so they're not really needed for this Instructable. Just a note for the future. Also, when people make suggestions/ask questions in comments (like alaskanbychoice), it's better to respond to their comment with "REPLY" because they will get a notification their comment has been replied to. That's just netiquette, though- again, good photos and good instructions.

hyrum32KT (author)2008-10-09

Yes, I missed that part. Thanks.

alaskanbychoice (author)2008-10-09

Because you are using a filter material that wasn't designed for an aquarium, can I suggest that you first rinse the filter you make under clear water for a while before adding it to your filter housing. I only mention this because there could be something in the filter material that could be harmful to the fish in water that might not be for us in the air. Good inst. otherwise.

sdallesasse (author)2008-10-08

Great idea, how has it worked out?

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