Fluval FX4 External Filter Review – Is it Worth It?

I’ve been running the Fluval FX4 for many weeks now on one of my African cichlids’ tanks, and so far it is great. The pump is very quiet, and the filter works well without any hiccups. I have not yet had to clean out the filter media at all.

I would recommend this product because it is a very high-quality unit for a reasonable price. It is good for both freshwater or saltwater setups, but I’d stick with freshwater unless you are using this as an additional filter to the main filtration system.

The only thing I’d recommend is to order the foam media separately if you want to replace the sponge pads because the sponge pads that come included are soft and thin.

Fluval FX4 Product Information

The Fluval FX4 is a great external filter. It has a very powerful pump that is very quiet and can turn over aquarium water very quickly. It has a very large, 1-gallon compartment, where you can place the bio-media, which is more efficient for biological filtration than a typical sponge or foam filter.

The FX4 comes with adjustable flow control, so you can control how fast or slow the water circulates through the filter. This is also convenient because it gives you the option of using this as an additional filter on top of your existing filter setup.

The FX4 includes an adjustable flow control knob as well as a valve on the bottom of the unit so that you can adjust how much water flows through each of them individually. This means that if you have two aquariums hooked up to this one filter, you can set one tank to run at 100% and another at 50% so they both get equal amounts of filtration.

The Fluval FX4 also is easy to clean. It comes with the media that is shown in the picture, but you can order other media separately to customize your filter to your needs.

Fluval FX4 Filter Specs

  • Filter Rating: for up to 250 gallons tanks
  • Pump Output: 700 gallons per hour
  • Filter Circulation: 450 gallons per hour
  • Size: 16 x 16 x 17 inches
  • Weight: 14 pounds
  • Wattage: 30 W
  • Power: Compatible with 110v-120v for North America, 60 Hz, 1 amp.
  • Warranty: 3-year warranty against defects in materials and workmanship (does not cover improper installation or damage caused by improper usage).

Fluval FX4 Pros

The FX4 is made of very high-quality materials and this product produces great results. The filter is very easy to maintain and use. Although the pump is very powerful, the filter has a low power consumption. The filter media works well to remove debris from aquarium water.

It is also extremely quiet for an external filter, so you will not have to worry about any loud noises in the room, where this filter is used.

The flow control on this filter allows you to make adjustments on the fly without having to disconnect anything or change out any media. This is very convenient if you are trying to find the optimal settings for your aquarium while you are still cycling it or if you just want more control over how much water is flowing through the filter.

This unit is easy to clean because all of the major parts can be removed without any tools needed. If you need to clean out any parts of this filter, simply take them out of their respective compartments and rinse them off in aquarium water.

I highly recommend this product because it makes maintenance easy while still producing good results for your aquarium water quality.

Fluval FX4 Cons

Although the filter is rated to 250 gallons tanks, I wouldn’t use this filter for such a large tank. I would recommend using the FX4 for up to 125-gallon tanks.

Also, the filter pads are pretty expensive if you want to replace them. I would recommend getting filter pads in bulk from other suppliers and cut them to the required size. This way you will save a lot of money.

If you have a 250 gallons tank, I highly recommend getting two of these filters. Or, you could get an FX6 as the main filter and Fx4 as secondary filtration.

Fluval FX4 vs Fluval FX6

While both models are great aquarium filters for larger aquariums, there are a few notable differences between the two.

  • The first is that the Fluval FX4 has a smaller capacity for biological media compared to Fx6.
  • The FX6 uses more electricity but has a larger pump output, capable of producing up to 925 gallons per hour flow rate.
  • The FX6 is slightly taller than the FX4, which ensures a larger filter media capacity.

Both filters can be installed very easily and their installation is very similar. You can download their manual here.

In my opinion, based on my own experience, these are some of the best filters available for larger, African cichlids tanks. They have proven to be extremely reliable and easy to maintain over time as well as provide excellent mechanical, biological and chemical filtration.

If you are looking for a filter for larger aquariums, then I highly recommend both Fluval FX4 or FX6.

Final Thoughts

The Fluval FX4 External Filter is a great unit for anyone who wants an effective external filter without spending too much money or having to deal with too much maintenance or hassle. It works well by itself or as an additional filter on top of your existing canister setup.

The only thing I’d recommend is ordering some extra sponge pads or other media so that you can completely customize this filter to your liking. I highly recommend this product because it produces great results while being very easy to use and maintain.

If you’re looking for a great external filter for your aquarium, I highly recommend the Fluval FX4 External Filter. It is a high-quality product that works well and is very convenient to use.  Simply connect it to your aquarium and plug it in.

It has a very powerful pump that produces a nice flow of water through the filter media, making your aquarium clear and your fish happy.


avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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