Aquarium Filters: 6 Types Explained & Reviewed

The sponge filter is a mechanical and biological filter usually powered by an external air pump. The air pump draws the water through the special sponge that then traps the bacteria inside.

The sponge filters offer several benefits. They’re very efficient for small tanks, especially when you have a second sponge filter so that when you have to replace the filter sponge you avoid the new tank syndrome that harms the fish. They’re very good for maternity or nursery tanks, as they don’t produce a strong current and there’s really no way that a small fish can be sucked into the sponge.

On the other hand, you’ll have to rinse or replace the sponge regularly to get rid of the bacteria it traps. It may also contain a carbon cartridge, and if you fail to replace that regularly then the waste chemicals it traps may release other toxic substances back into the water.

The XY-380 Biochemical Sponge Filter is a good example for this category. It can be used for tanks ranging from 10 to 55 gallons. Its base is weighted so it doesn’t float, and its cylindrical design eliminates “dead space” between the filter. It’s also very easy to clean and quite affordable, which make it one of the best sponge filter models you can buy.

This is a filter that draws the water through a box inside the tank. Inside the box, you can place some types of filter media, which can be batting or filter floss plus a little activated carbon. The floss removes particulates why the activated carbon extracts toxins.

One advantage of this type of filter is that you can carry out various filtering methods. The floss offers mechanical filtration that removes particulates. The activated carbon removes harmful chemicals. And the sides of the box (as well as the floss and the carbon) can also work as a bacteria bed to trap bacteria. It’s quite efficient, especially for a small volume tank.

But the problem with it is that it can take up a lot of space, and in a small tank you don’t have a lot of space for your fish to begin with. And since you also have lots of filter media, you’ll also need a lot of maintenance. You’ll also need a second biological filter, so you don’t get new tank syndrome when you remove the bacteria bed in the box filter to clean the filter.

Lee’s Triple-Flow Corner Filter is one of the best fish tank filter options for this type of filter. It’s very efficient in moving the water through, as its design involves 3 intake vents. It can be used for tanks of up to 100 gallons, and it’s ideal for isolation or breeder tanks. Beginners will also find it easy to use.

This is a plastic grate filter that sits under the tank gravel. Air pumps or power heads moves the water through the filter and out the lift tube. The gravel becomes part of the filtration process, as it offers mechanical filtration by catching the bigger particulates. Then the filter plate, the tank bottom, and the lift tube also become beds for trapped bacteria.

These are very effective biological filters, and with some mechanical filtration bonuses as well. Unlike the earlier filters we discussed, you don’t have to change your filter media with your under gravel filter. They’re very easy to maintain and it’s the cheapest type of filter to run. All you need to do is to clean the gravel when you do your regular water change.

However, some do have carbon cartridges that must be replaced regularly, but you should just take them out instead. These things don’t offer much help when in an under gravel filter, and can pose a lot of problems instead. Also, it’s not designed to maintain your tank on its own. You need it to work with other types of filters.

This kind of situation is illustrated by Lee’s 40/55 Premium Undergravel Filter. It comes with carbon cartridges, and you simply just don’t attach them. Without this feature, it’s one of the best under gravel filter models around. It offers 2 plates that are enough to cover the bottom of a 48-inch long tank. Its quality is very good and its works extremely well even with just a power filter.

This is also called a power filter, and it’s very common with very affordable tanks. It usually hangs on the back (hence its name), and inside the container you have several filter media types that can provide chemical, mechanical, and/or biological filtration.

It’s a very good particulate filter, and it works well enough as a biological filter. And because it hangs in the back, it doesn’t take space away inside the tank which your fish and plants can use instead.

But unless you get the best power filter around, you’re probably going to get poor chemical filtration. And it can be inefficient, as often the water it takes in is also the water it has just recently churned out and therefore already filtered. The evaporation rate is also a problem.

With the right unit, however, you can minimize these drawbacks. One good example here is the AquaClear Power Filter, which can handle up to 20-gallon tanks. It’s one of the best hang on back filter models available today.

It’s easy to install and it comes with a 2-year warranty. Its design ensures that the water really goes through your various filter media, and you have various types here. It’s equipped with AquaClear Foam, Activated Carbon and BioMax and Cycle Guard so that you have all the filtration methods covered.

As one of the best HOB filter models around, its pump is strong enough to get a filtration volume that’s 7 times larger than many of its comparable competitors. But that pump is energy efficient too, which can help reduce your operating costs.

This type of filter gets its “wet/dry” name because the filter media is exposed to the aquarium water (that’s the “wet” part of the name, which hopefully you’re old enough to grasp) and to a large amount of air (which, by process of elimination, is the “dry” part of the name). As for being called a trickle filter, it’s because the water trickles through the biological filter media

The main benefit of the trickle filter is that it makes for an excellent biological filtration system. If you have a large aquarium or a saltwater fish tank which absolutely need an extremely efficient biological filtration system, then this type of filter is ideal. It doesn’t need much maintenance at all, especially when you use it with a mechanical filter.

On the other hand, it can be very difficult and expensive to set up, unless you’re very experienced already. And it really doesn’t do much at all for mechanical and chemical filtration. The evaporation rate is also a cause for concern. It’s also only ideal for bigger tanks especially for 80 gallons or more.

One example of this type of filter is the Aqueon 34500 ProFlex Sump Model 1, which can be set up as a wet/dry filtration system with the BioMedia Accessory Pack. Interestingly, you can also set it up for the Berlin filtration method or you can use it as a refugium. This can be the best wet dry filter for you, as it is very durable, and it even comes with a lifetime warranty against leaks. But you’ll need to know what you’re doing when you set it up.

Here you have a large canister for a filter, so you can just picture the filter media it can hold. I’ll have an article here shortly which will describe it more fully.

Suffice it to say that when it comes to providing mechanical, biological, and chemical filtration, it’s probably the most effective. Its filtering power and efficiency are incomparable.

However, with great power comes lots of complications when it comes to the setup, so you’ll need a bit more effort before you can use it properly. And it can also be quite expensive.

The Fluval External Filter is a good example of this. It works for up to 100 gallons, and its impeller comes with sound dampening design so that you don’t have a ruckus when you push all that water through the filtration system. The build quality is great too, and you also get a 3-year warranty.