Why Use Aquarium Filter Floss and Where to Get it Dirt Cheap?

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Your fish tank’s water looks somewhat cloudy and now mechanical filtration seems like a good idea. Or, perhaps, you want to take the aquarium’s clarity to the next level and want to see things crystal clear as if were floating in the air? Should you use filter floss media and is it worth it, compared to a sponge? Or you’re simply trying to think of a DIY filter floss as an alternative? What’s the frugal approach here? Could cheap polyester filter floss be the solution to all of your problems? Let me help.

Why should you use a fish tank filter floss in the first place?

In aquatic systems mechanical filtration is used to capture fine water-polluting particles. These can result in unsightly or even hazardous water quality. In an aquarium, it makes sense to implement filter floss for the following reasons:

Using filter floss media is the fastest and most efficient way to achieve crystal clear aquarium water. It will mechanically filtrate detritus that will otherwise spoil your water quality. Filter floss should be changed regularly to prevent a buildup of decomposing debris. It will also catch microscopic bubbles, responsible for cloudy water. You can expect clear aquarium water in about 3 to 4 days.

Note that filter floss is way more efficient than a sponge in mechanical filtration.

At first glance, sponges will appear cheaper in the long run.

However, this may not be the case if you know what kind of filter floss to get and where to look.

Sometimes, the haziness of the water is caused by an actual, living bacteria bloom which contributes to a cloudy fish tank with a white milky look.

Other times overly-abundant microalgae spores (“green pea soup”) could be the possible cause behind the “dirty” look.

In these cases, mechanical filtration will not be enough.

You will need to sterilize your water with ultraviolet light to prevent further reproducing.

Other advantages

Filter floss’ a rather controversial topic.

It is said to accumulate nitrites (link to where I explain how to handle that in detail).

The logic to that is that the nutrients will collect in it, and start decomposing there.

You’ll have those in the aquarium anyway, whether you choose to circulate them or not.

They will just be more spread out. By collecting the detritus and periodically removing the floss you are actually doing more about filtration than without it.

Another impressive outcome of using filter floss I found is that I don’t really need to wash my other filter media.

The floss does almost all the filtration.

I rarely find myself rinsing the media where the beneficial bacteria live.

I now do it, perhaps twice or three times a year. What a relief…

By the way, in marine tanks, the back chambers can get nasty with time.

That is if you don’t stop your filters during feeding or running them too early afterward.

Filter floss media will significantly reduce the build-ups in these chambers over time.

Using Poly-Fil (polyester fiberfill) in the aquarium filter?

Changing filter pads can turn out expensive in the long run. Here’s how to get around that by using Poly-Fil in the aquarium:

To avoid costly “aquarium-grade” filter media you can simply replace it with 100% polyester quilting material. For extra efficiency – go for the high-loft batting. The high-loaf polyester batting is thicker and therefore more convenient to use for filtering purposes. A good brand to look for is FairField’s Poly-Fil quilt batting.

It is completely fish-safe and inert.

It’s mad efficient as well.

It will “polish” your water extremely well, making it appear as if your fish are floating in the air.

You can either use it for your display sessions or all the time. It’s up to you.

I use it full-time.

The quilting batter is bonded which means it will not have loose fibers. So the small fibers will remain where they belong, not being able to clog your filter.

How to use it in an aquarium?

This is how to use this type of filter floss in your aquarium filtration:

  1. Use sharp scissors when cutting the pieces to prevent chewing.
  2. Place it wherever you want in your filter.
  3. I often choose to place mine right before the bio-media.

  4. Control how thick the layer will be by folding it if needed.

Having this product as filter floss does not require as much diligence as well. I change mine every 4 to 6 days.

It can occasionally be used in canister filters as well. In mine, I add it every month or so and change it if I notice a reduced water flow.

If you’re a proud owner of one of the better canister filters out there you should have plenty of room to experiment with the added quantity.

And I get crystal clear water for my display tanks.

It’s a perfect solution for sump chambers as well.

Some users report rinsing the DIY floss pads and reusing them. I don’t do that. The stuff is so affordable that I choose to change it whenever.

Talking about price, you can purchase a pound of the stuff for as little as 6 to 10 US dollars or the equivalent of that in your country.

Where to buy it?

Here’s how to save money when looking to buy Poly-Fil:

Poly-fil can be found at Walmart and other crafting and fabric stores if you have the time to look for the right one.

Just make sure it is 100% polyester and it hasn’t been treated with any chemicals.

Mold and mildew-resistant fabrics have chemicals in them that are highly toxic to fish.

If you’re a busy person, or in a hurry, or simply like to shop from your couch you can purchase it on Amazon here. I’ve chosen the right product in the link. It comes in a huge bag that contains a 45″ x 60″ (or 1.14 x 1.53 meters) sized sheet.

Note: You may notice the “flame retardant” label on the bag.

Many fishkeepers know that anything that is flame retardant has been treated with chemicals that are lethal to fish.

Worry not though.

In this particular case it means that the polyester has inherited flame retardant properties.

Pure polyester is such on its own, because of its chemical bonds and it does not require treatment.

The term “flame retardant” does not refer to a particular set of chemicals, but rather a function.

Yet another inexpensive route – pillow stuffing

I did promise you a dirt cheap option, didn’t I? This is it. With this method you’ll get the most for the least money:

You can find filter floss in pillows.

This is probably your most inexpensive alternative.

Again same rules apply – 100% polyester, undyed, and unscented to ensure fish safety.

Go to the store and find the cheapest pillow possible. The stuff inside will last you for more than a year, if not 2, depending on the tank you’re filtering.

Doing some calculations you’ll discover that this way you’ll save a fortune on filter pads in the long run.

It’s as effective as the poly-fil quilt material in making your water look like air.

The polyester pillow stuffing can be used all over your filter.

It can even act as your sole bio-media, housing beneficial bacteria in it.

This is not a claim, I have tried it myself and it worked perfectly fine.

My tank remained cycled despite water and decor changes.

So that’s another couple of bucks in your pocket.

Another good way to put the pillow filter floss to use is to reduce your filter’s intake flow.

If you’re having fry (juvenile fish) in the aquarium they are potentially at danger of being sucked in.

Not many filters have an adjustable flow rate so you can use the filter floss to control it while doing some extra filtration.

If you do choose to use it this way, you can only replace the floss in the initial uptake pipe, as it will wear out in 3 to 5 days.

The pillow polyester filling does have one disadvantage though.

Its fibers are really fine and it may clog your filter’s propeller. It’s annoying to manually unclog that.

Why would I recommend it then?

There’s an easy solution to the problem, of course.

Just use some sort of mesh bag to contain it.

Though a pantyhose sock will do a decent job at that you may want to go the extra mile.

Seachem makes something that may come in handy.

It’s called “The Bag” and at the time of writing costs just under 9 bucks.

Which is pretty close if not lower-priced than the nylon stocking.

Yet, it’s a 180-micron mesh that’s able to contain even the smallest media on the market.

The price is so low because it is originally designed to hold Purigen (another product of Seachem).

This way you’d need to buy both when in need of the latter.

However, in this case, you can use it to house your pillow filter floss and prevent propeller clogging.

See the micron bag here (at Amazon).


Given how insignificant the cost can be and how little maintenance is required, I think using filter floss in a fish tank is a no-brainer.

It will provide your aquarium with a stunningly clear view of your fish.

And what is there to fishkeeping other than being able to enjoy your aquarium in HD, right?

Do leave a comment if you have additional questions.

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