6 Best Mechanical, Biological, & Chemical Filter Media 2023

It can be difficult deciding on which filter media, whether biological, mechanical, or chemical, is the best.

Every tank is different and what works in a 15 gallon tank probably won’t work in a 100 gallon.

However:

In this article, I’ll take you through the types on filter media, discuss how to choose, and review my choices for the best filter media available.

product Table overview for Filter media

Preview
Product

Aquapapa Bio Sponge Filter Cut-to-Fit Pad for Aquarium Fish Tank Koi Sump Reef 25”x 4.75”x 0.75”

Aquapapa Bio Sponge Filter Cut-to-Fit Pad for Aquarium Fish Tank Koi Sump Reef 25”x 4.75”x…

Encompass All Premium 50 Micron Polishing Filter Pad - Cut to Fit 36x24

Encompass All Premium 50 Micron Polishing Filter Pad – Cut to Fit 36×24

Fluval Biomax Bio Rings, Biological Filter Media for Aquariums, 17.63 oz., A1456

EHEIM Substrat Pro Biological Filter Media (Sintered Pearl-Shaped Glass) 1L

POLYBIO Poly Filter PAD 4 X 8

Last update on 2023-03-01 / Commissions Earned / Images from Amazon Product Advertising API

Types of Filter Media and What They Do

Let’s start by going through each type of aquarium filtration media and their purpose.

Mechanical

Mechanical filtration is really simple. All it really does is trap particles floating in the water.

So little bits of sand, dead plant material, pieces of uneaten food and solid fish waste gets stuck in mechanical filtration media.

This is great because all that gunk floating around in the water column really does make the tank look dirty and less attractive.

Biological

Biological media is arguably the most important. Without it, it wouldn’t be possible to maintain aquariums at all.

All fish and invertebrates put out waste. All that poop and pee sinks down to the bottom of the aquarium and builds up in your substrate.

I know, super gross, but it’s the truth.

As the waste begins to break down, it puts off ammonia (NH3), which is highly toxic.

Left on its own, ammonia would keep building and building until the water in your tank became a toxic soup that would kill any fish or invertebrate exposed to it.

Lucky for us, and our fish, there are species of beneficial bacteria that grow in the filters of our tanks that help process fish waste.

One kind of bacteria converts ammonia to something called nitrite (NO2 -1), which is still very toxic. But another kind of bacteria quickly turn the nitrite to a much safer compound called nitrate (NO3-).

But all these handy bacteria don’t just swim around in the water column. They have to attach themselves to something in an area with lots of water flow. That way, they’ll have the oxygen they need to breathe and the fish waste they need to eat.

This is where biomedia comes into play. It acts like a “house” for beneficial bacteria in your filter. The bacteria attach themselves to the biomedia, and start to reproduce, eventually building up a colony big enough to process fish waste for you.

Pro Tip: For more information on beneficial bacteria in your aquarium, check out our article about the Nitrogen Cycle.

Chemical

The purpose of chemical filter media is to remove substances in your water through some sort of chemical reaction.

The most common chemical filtration media is activated carbon, which removes things like tannins and dissolved organic compounds.

There’s a lot of debate about whether or not you should run chemical filtration in your tank full time.

Some people are in favor of running chemical filtration full time.

Others argue that you only need to use chemical filtration at special times, like an unforeseen ammonia spike or to remove medications from the water.

How to Choose Your Filter Media

The type of filter you have is a key factor when you’re choosing filter media.

A lot of hang-on-the-back filters have a limited amount of space for media, so you have to go with what will fit.

Pro Tip: I recommend choosing a hang-on-the-back filter with the most room for media, like a Hagen Aquaclear or a Seachem Tidal Filter. You can pack these with biomedia instead of relying on small filter cartridges.

Personally, I always include some sort of mechanical filter media, to grab detritus out of the water, and then just fill the rest of the space with as much biomedia as I can.

I want to maximize the number of beneficial bacteria in my filter, so I provide as much surface area for them as possible.

I don’t run chemical filter media unless I need to clear out medications. I just don’t think you need chemical filtration in an established tank and it really does jack up the monthly cost of running your tanks, especially when you have as many as I do.

There are plenty of aquarists out there who would argue for needing chemical filtration all the time, this is just what I’ve found works for me after many years of keeping fish.

Best Mechanical Filter Media Reviewed

Let’s start by going through the best mechanical filter media

1. AquaPapa Sponge Filter

Tough synthetic sponge material that can be cut to fit any filter.

I love that you can spray this out with your hose and reuse it again and again.

It’s a medium coarseness, so you’d still need a finer filter media to catch really small stuff.

Pros:

Can be cut to fit any filter
Can be cleaned and reused

Cons:

Won’t catch really small debris

Aquapapa Bio Sponge Filter Cut-to-Fit Pad for Aquarium Fish Tank Koi Sump Reef 25”x 4.75”x 0.75”

Last update on 2023-03-01 / Commissions Earned / Images from Amazon Product Advertising API

2. Encompass 50 Micron Polishing Pad

This is a super fine mechanical media meant to “polish” your water by catching super fine particles.

It comes in a large 36”x24” (91×61 centimeters) roll. You can cut pieces to fit any size or shape filter. The big roll means that you can cut out lots of pieces making it a much better value than filter cartridges or pre-cut polishing pads.

It would be a great addition if you’re using coarser media, like the AquaPapa sponge.

This will get clogged up easily since it is such a fine media and need to be swapped out for a fresh piece frequently. And it won’t hold up to being reused so you’ll need to add a fresh piece each time.

Pros:

Catches super fine particles
More economical than other polishing pads

Cons:

Can’t be reused
Clogs up quickly

Encompass All Premium 50 Micron Polishing Filter Pad - Cut to Fit 36x24

Encompass All Premium 50 Micron Polishing Filter Pad – Cut to Fit 36×24

Last update on 2023-03-01 / Commissions Earned / Images from Amazon Product Advertising API

Best Biological Filter Media Reviewed

Now let’s go through some of my favorite types of biological media.

1. Fluval Biomax

Fluval Biomax is made up of highly porous ceramic material. It’s covered in all sorts of little nooks and crannies that are perfect for beneficial bacteria.

The hole through the center of the ceramic noodles also lets water flow through each piece, allowing for more oxygen to reach every square inch of media.

This is a durable media that will last you for years and is small enough to fit in many hang-on-the-back filters. Just put it in a mesh bag and place it inside your filter.

Pros:

Lots of surface area for biomedia
Small enough for most hang-on-the-back filters
Durable

Cons:

None that I can think of!

Fluval Biomax Bio Rings, Biological Filter Media for Aquariums, 17.63 oz., A1456

Last update on 2023-03-01 / Commissions Earned / Images from Amazon Product Advertising API

2. EHEIM Substrat Pro

This media is made up of irregular spheres of sintered glass. You can put this into a mesh filter bag to go into your hang on the back or canister filter.

Provides 1800 square feet of surface area for every gallon of volume, plenty of room for a thriving bacterial colony.

Pros:

Creates lots of surface area for bacteria
Large volume of media for the price

Cons:

I can’t think of any!

Sale

EHEIM Substrat Pro Biological Filter Media (Sintered Pearl-Shaped Glass) 1L

Last update on 2023-03-01 / Commissions Earned / Images from Amazon Product Advertising API

Pro Tip: You may see some biological filter media that say they need to be replaced every 6 months or so. I really have to disagree with this and say that they should only be replaced once they start to physically degrade. This can take years.

Best Chemical Filter Media Reviewed

Now onto my top picks for the best chemical media.

1. Seachem Purigen

Purigen is made from a unique polymer that traps wastes and other impurities in the water. It is superior to carbon because it absorbs a wider variety of impurities.

It will change colors over time, letting you know when it is exhausted.

Purigen can be “recharged” by treating it with bleach so you can reuse it.

It might seem expensive, but 100 milliliters is enough to filter 100 gallons (378 liters).

My one nitpick is that Purigen can remove wastes before beneficial bacteria can eat them. This can affect the size of your bacterial colonies and make it necessary for you to keep using Purigen to keep up with fish waste.

Pros:

Excellent removal of organic wastes
Color lets you know it’s exhausted
Can be recharged
Economical

Cons:

Removes waste before biofilter can feed on it

No products found.

2. Poly-Filter by Poly-Bio-Marine

Poly-Filter looks like regular filter floss but it’s actually a potent chemical filter that removes ammonia, nitrite, nitrate, copper, soluble medications, phosphates and tannins.

Yep, all of that.

It also changes color and lets you know it’s exhausted and can be cut to fit any size or shape of filter.

Just like Purigen, Poly-Filter can starve out beneficial bacteria and affect the size of your bacterial colonies.

Also, there is no way to recharge Poly-Filter, so it’s not the most economical media.

Pros:

Filters out a wide range of substances
Changes color when exhausted

Cons:

Can’t be regenerated
Can be pricey over time

POLYBIO Poly Filter PAD 4 X 8

Last update on 2023-03-01 / Commissions Earned / Images from Amazon Product Advertising API

Deciding On Which Filter Media to Pick for your aquarium

It’s hard to pin down exactly which filter media is the best, since everyone’s tank is a little different. What works for a 5 gallon nano setup won’t work for someone’s 100 gallon planted tank.

For me though, I would have to say that maintaining a healthy biofilter is absolutely critical. It’s the one thing that you really can’t do without.

I highly recommend maximizing your biological filtration as the number one way to ensure long-term success for your tank.

Preview
Product

Aquapapa Bio Sponge Filter Cut-to-Fit Pad for Aquarium Fish Tank Koi Sump Reef 25”x 4.75”x 0.75”

Aquapapa Bio Sponge Filter Cut-to-Fit Pad for Aquarium Fish Tank Koi Sump Reef 25”x 4.75”x…

Encompass All Premium 50 Micron Polishing Filter Pad - Cut to Fit 36x24

Encompass All Premium 50 Micron Polishing Filter Pad – Cut to Fit 36×24

Fluval Biomax Bio Rings, Biological Filter Media for Aquariums, 17.63 oz., A1456

EHEIM Substrat Pro Biological Filter Media (Sintered Pearl-Shaped Glass) 1L

POLYBIO Poly Filter PAD 4 X 8

Last update on 2023-03-01 / Commissions Earned / Images from Amazon Product Advertising API

Filter Media FAQs

What order should you place filter media in the filter?

You should order your media like this:

Mechanical media – this catches all the large particles and gunk so they don’t clog up your chemical or biomedia. If you’re using different grades of mechanical media, make sure to put the coarsest media first, then the next coarsest, etc. That way, bigger particles are caught by the coarser media and aren’t clogging up the finer one.
Biomedia media
Chemical media – you want chemical media to be last so that it’s not getting clogged up with detritus and isn’t removing things like ammonia and nitrite before biomedia has a chance to convert it.

How often should you clean filter media?

This really depends on several different factors, like the size of your tank, stocking levels, kind of filter, type of fish, type of media, etc.

Mechanical media needs to be cleaned out once it gathers up enough detritus that it starts to get clogged and restrict water flow.

This might take months for coarse media and only a few days with fine media. It really is a process of trial and error to figure out the needs of your own tanks and filters.

Biomedia really doesn’t need to be cleaned other than to clear off surface gunk by giving it a good rinse in dechlorinated water.

You don’t want clean it too much because that could kill the beneficial bacteria that grows on or in it.

You don’t really need to clean chemical media.

How often should filter media be changed?

Some mechanical media can be sprayed out with a garden hose and then used again and again. This is especially true of filter sponges and tough, coarse media materials.

These only need to be changed out when they start to fall apart.

Many finer mechanical media won’t hold up to being cleaned and so need to be changed out as soon as they start to become clogged.

I really don’t recommend changing out biomedia unless it is starting to physically degrade. When you remove biomedia, the beneficial bacteria growing on its surface goes with it.

Even if you replace it with new media, it can take a few weeks for the bacterial colonies to build back up to their former levels.

Without sufficient numbers of bacteria, you run the risk of ammonia and/or nitrite spikes that can stress and kill fish.

If you do have to swap out biomedia, only replace half at a time so that you don’t lose all of your beneficial bacteria at once.

How to clean filter media?

Depends on the type:

Mechanical

This all depends on the kind of media, but many can just be sprayed out with a garden hose or kitchen sink sprayer to rinse out algae and other detritus.

Biological

You should only swish biomedia around in dechlorinated water. It’s not a good idea to actually get this kind of media too clean since that would kill the beneficial bacteria that grows on it.