SunSun HW-603B External Canister Filter Review

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Are you looking to replace your aquarium’s filter system? Or perhaps your brand-new tank needs some cleaning gear that performs well on a budget.

The SunSun HW-603B External Canister Filter may be your perfect fit. It works on tanks up to 20 gallons, is easy to set up and maintain, and is very inexpensive.

SunSun HW-603B External Canister Filter

With that said, not everyone had a great experience with this canister filter. Some users had it leak, found it arrived damaged or encountered a range of malfunctions. Is that the common opinion or the rare case?

Before you make your final decision, let’s take a closer look at the SunSun HW-603B External Canister Filter.

SunSun HW-603B External Canister Filter: The Details


  • Weight: 3.7 lbs.
  • Dimensions: 6.5 X 6.5 X 11 inches.
  • Filter Capacity: 20 gallons.
  • Flow Rate: 106 GPH.
  • Media Stages: Mechanical, biological, and chemical media.
  • Self-Priming or Standard: Self-Priming.



This SunSun External Canister Filter works for any aquarium with a capacity of 20 gallons. While that’s not a huge tank, it is appropriate for smaller home aquariums that contain a selected number of fish.

This filter cycles through the full 20 gallons every 12 minutes so, ensuring your tank is kept clean and free of any debris (such as leftover fish food or waste).

It’s a bite-sized filter for a bite-sized job – and performs well in this regard.

Three-Stage Filtration

The SunSun canister filter also has a three-stage media filtration system.

This means that the water will go through a mechanical, biological, and chemical media, so as to guarantee every particle or unwanted thing in the water is removed.

The filtration media itself does not come included, but the filter supports activated carbon, ceramic rings, and bio-balls.

Each form of media cleans a different particle out of the water, providing a healthier environment for your fish.

Flow Rate

The flow rate on this external canister filter is 106 gallons per hour. As noted above, that means that the filter can work through 20 gallons of water over five times in an hour.

This results in your water being thoroughly cleaned and free of impurities on an extremely regular basis.

Types of Water

While some filters suit only freshwater or saltwater exclusively, this SunSun canister filter can be used in either.

As such, if you one day upgrade to a saltwater aquarium, there’s no need to purchase a second filter or risk destroying your current investment.

This filter is built with diversity in mind and delivers a punch to whichever aquarium you attach it to.

best canister filter for small tanks


  • Input and output discreteness.
  • Barrel head.
  • Water pump.
  • Water inlet connector with flow control valve.
  • Upper filter board.
  • Under filter board.
  • Input curvy bar.
  • Output curvy bar.
  • Spray bars.
  • Water outlet.
  • Input bars.
  • Input cover.
  • Coarse filter sponge.
  • Suction cup.

SunSun HW-603B External Canister Filter Review

The Positives

Easy to Set Up

Whether you are an aquarium novice or have been establishing and running tanks for years, there’s no worry of this SunSun External Canister Filter overwhelming you. Most testers claimed the set-up process was very easy.

To begin, you should unclasp the four clips on top of the filter and remove the cover. Insert the media of your choice and put the cover back on, pushing down the clasps to secure them.

Connect the suction attachment to the filter’s head, and put one inlet and outlet tube at the base of the filter. Screw them into the designated areas and then prime the filter.

Insert it onto your tank – and then you’re done! After the filter is set up, you can attach the spray bar in whichever location is most convenient.

Easy to Use and Maintain

Aside from changing the media and cleaning any waste that ends up in the filter, there’s very little input needed from you.

The use and maintenance of this filter are straightforward and mostly hands-off. Once your media is placed within the canister, it needs to be changed once every few months – nothing more! It’s that simple.

You may want to check in on malfunctions or mishaps now and then, but very few users ever reported an issue. The filter mostly runs itself.


This is by far one of the least expensive filters on the market. At just over $30 on Amazon, you certainly won’t break the bank with a SunSun.

SunSun HW-603B review

Since the media isn’t included, this low price frees up your budget to shop for the exact brands you desire. Although it’s always nice when everything comes included, at this price, it can definitely be excused.

This low price means great news for those on a budget and even beginners looking to dip their toes into fishkeeping.

For those that want to make a more customized home for their fishy friends and accessories, this allows you to easily build on tank necessities without having to stick to a rigid setup. You can let your creativity shine as you learn without breaking the bank.

Efficient and Powerful

Despite the prize and size of this canister filter, what’s the use if it doesn’t do its job? Fortunately, you won’t have to worry about this SunSun.

Users loved how clean this filter got their aquarium, usually taking no time at all. And since this filter requires little effort from you, you can kick back and let it get the job done.

If you’re looking for a filter to really get your tank sparkly clean without having to dig deep into your savings, this SunSun HW-603B may just be the canister filter you’re after.


An efficient filter doesn’t have to be noisy, and SunSun has done a great job at showing that. Users of the canister filter made sure to point out how quiet it is.

A noisy filter can cause disruptions depending on where you place your aquarium and depending on your noise sensitivity levels. However, you won’t have to worry about a thing with the HW-603B.

This opens up a variety of options of where you can place your tank. If you want to fall asleep to your soothing aquarium you won’t have to fret about waking up to a gurgling or whirring tank.

This filter allows your aquarium to shine without it stealing all the attention.

The Negatives

Not Everything is Included

With that said, a couple of users felt more items should have been included with the purchase – primarily the media.

It does come with a few filter sponges, but the activated carbon, bio balls, and ceramic rings must be purchased separately.

This isn’t a huge issue, because the filter is so inexpensive, but you should be aware that additional purchases will be necessary.

The filter media is crucial to the functionality of the entire canister, so you can’t avoid this.

SunSun HW-603B External Canister Filter

Some Leak Issues

Unfortunately, some users did have the filter leak. A couple testers had it leak shortly after it arrived, while others had it work fine over several months – only to come home to a great deal of water on the floor or around the tank later on.

This may be a “you get what you pay for” situation. While the filter’s excellent price point is tempting, the quality of the materials may be lacking. A more expensive filter may provide more guaranteed quality.

Some Problem Solving to Be Expected

In some cases, the filter did not work at all because it needed to be toyed with for several minutes before functioning.

This issue may be a result of insufficient pressure in the filter; as such, the water can’t properly cycle through it.

While the product page states that you won’t need to siphon the water yourself, some testers have stated otherwise and couldn’t prime the pump in any other way.

Shipping Issues

Additionally, there were situations where the canister filter arrived broken or damaged, making it so users couldn’t even test it. This can be due to issues with shipping and not the manufacturing itself.

While there is always Amazon’s 30-day money-back guarantee, there were also cases where the replacement filter arrived broken as well.

This was by no means a widespread problem, but it is worth noting. If the low price point isn’t worth having to replace it multiple times, even free of charge, then it’s wise to keep shopping.

Poorly Written Instructions

This filter is thankfully easy to set up. Following the directions in the manual, however, will prove to be more confusing.

Users noted that the instructions included with the SunSun HW-603B were harder to follow than actually getting this filter installed and operating. The included instructions miss some details, and the translation has led to limiting advice.

While this doesn’t take away from the functionality of the filter, if you were looking for a well-guided instruction manual, SunSun fails in this department.

best canister filter for small tanks

Overall Verdict

After sifting through all the positives and negatives, we are recommending the SunSun HW-603B External Canister Filter.

While the reasonable capacity, the easy maintenance, and the low price are all great, some users did have issues with leaking and malfunctions – namely, it was difficult to prime.

With that said, if you’re willing to exercise your Amazon warranty for those rare duds, you can enjoy a cost-effective filter which provides quality results.

You’ll need to make additional purchases, but can still ensure your salt- or freshwater aquariums (or both!) are clean and pristine for far less than competing products allow.

Where to Buy the SunSun HW-603 External Canister Filter

SunSun has a knack for manufacturing affordable and accessible filters that are perfect for a variety of aquarists.

With a number of filters and other aquarium items under their belt, SunSun continues to gather positive customer feedback on their brand, allowing them to grow in popularity.

SunSun is starting to become a better-known brand in the aquatic world, making it easier to find their products like the SunSun HW-603 External Canister Filter available both in-store and online.

With a growing line though, some items may be harder to find than others. While it’s usually best to check pet, aquatic, and specialty stores, you can kick-start your search with the following online retailer.

And of course, you can also find this canister filter on Amazon.

SunSun HW-603B External Canister Filter

That’s the end of this SunSun HW-603B review. Curious to give this filter a try?

SunSun HW-603B External Canister Filter Rated
  • Quality of Filtration
  • Build Quality
  • Accessories
  • Ease of Use
  • Value for Money

FCG Verdict

What really catches the eye on this SunSun HW-603B External Canister Filter is its price. Pair an affordable product with convenience and efficiency and you may have a winner.

This filter does with some cons, but there are just as many pros to combat them. If you’re looking for a cheap filter for your small tank, this may be the one for you.

>>> Check current price on Amazon.

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