SunSun HW-304B Pro Canister Filter Review

Review Summary

In this canister filter review, I break down the impressively specced Sunsun HW304 B Pro. Despite its bargain price tag, this is one of the better canister filter products on Amazon today. Included are three spacious media trays, a high output 525 GPH pump, all of the hoses required, and a built-in UV lamp to polish your water further!

Sunsun Hw304B 525GPH Pro Canister Filter Kit

Sunsun HW304 B Pros:

  • High capacity media baskets
  • UV sterilizer built-in
  • High rate of water flow
  • Little to no water bypass

Sunsun HW304 B Cons:

  • Flow rate not adjustable
  • Basic media included
  • Not as quiet as comparable models
  • Terrible instruction manual

Things to Consider Before Buying a Canister Filter

Canister Filter Size:

Unfortunately, for all the power they provide, canister filters are fairly large compared to most common filters. Even average-sized units like the Sunsun Canister filters still need plenty of storage space under your aquarium stand.


Customization is the major feature canister filters have over a traditional power filter. But if there aren’t enough filter media trays, the unit is far less customizable than you might prefer. Filtration media is important regardless of the type because different media allows you to perform different tasks.

If I need additional biological filtration capacity, I can add ceramic rings or bio-balls. If I’m looking for chemical filtration media, the trays provide room for zeolite or activated carbon. The more options I want, the higher the price usually is.


Let’s face it; compared to nearly any hang on the back power filter, a canister filtration system is going to be significantly pricier. Still, this is what you buy if you want to make sure that your water quality is always perfect!

Looks & Build Quality

If looks are important to you, there’s no doubt that the Sunsun Canister Filter is one of the best looking on the market. Sunsun filters have a style somewhere between minimalist and Star Wars in character, and I absolutely love it!

Considering how affordable this unit is, I’m very surprised by the build quality! The Sunsun filter doesn’t feel significantly cheaper compared to a Filstar or other comparable budget unit. Something premium like a Fluval FX6 has heft and durability that the Sunsun doesn’t. But that’s what you get for over double the price.

The unit also uses rubberized feet to keep the Sunsun canister filter stable and reduce noise that often comes from the pump motor’s vibrations. The dampening helps, but I’ve noticed that the canister filter impeller is slightly noisier than other brands. Still, stored in under a stand with the door closed, I wouldn’t say it’s so loud that it’s a problem.

Four locking mechanisms ensure that water remains pressurized and fully contained until you’re certain you’re ready to perform some maintenance. Even if one latch is disturbed during water changes, the unit won’t burst right open.

Setup & Priming

Unfortunately, the included directions with this item are a disaster. Luckily, Youtube content ensures that no matter how niche the product, you’ll always be able to find someone who has already figured out the hard parts for you!

Once you’ve opened up the aquarium filter, arrange each of the media trays in front of you. Unlike some filters, the SunSun HW 304B includes 1 lb of activated carbon, 1 lb of ceramic rings, and several bio-balls to get you started. I still recommend you make sure to pick up an additional filtration media option to make the most out of your canister filter.

Next, you’ll need to fill the unit with tank water and attach the included hoses to the upper portion of the Sunsun filter. The ultraviolet sterilizer uses a UV light bulb that needs to be installed into the upper portion, so don’t forget to install it before resealing the unit.

Like all of the best canister filters on the market, the Sunsun HW has a self-priming pump to keep you from having to fuss with getting tank water into the hoses. Older aquarium canister filters were a real hassle to prime because it wasn’t easy to prime them. Self-priming brands are what I always recommend!

There is no included spray bar, but you can purchase one separately for a very reasonable price. A spray bar helps diffuse the high flow rate of this aquarium canister filter across a wider area.

Operating the Filter

One aspect of the Sunsun Canister Filter that you should note is that there is no flow control. With the HW304 b, you’re locked into a flow rate of 265 gallons per hour. Still, as long as your tank is large enough, this shouldn’t really be an issue.

The built-in UV sterilizer is a feature that really helps the Sunsun stand out from other models. Typically, a UV sterilizer is a separate device that uses extra power and takes up more space.

With even the best filter, many tiny organisms can float past the filtration media. In a sterilizer, the water is pumped past a bulb that emits UV light. This high energy radiation blasts the DNA of algae spores, bacteria, and other microorganisms to pieces!

By killing algae spores and bacteria, the water is ultra-purified before returning to the aquarium. An ultraviolet sterilizer is the most powerful tool you can own to control green or cloudy water issues.

Near the ON/OFF switch is a clear window that lets you see the faint purple glow of the UV bulb itself. If it fades or goes out entirely, you’ll know it’s time to replace the bulb.


I’d say that the price is one of the best features of this filter. It can compete with units twice the price. Despite being a non-name brand model, I would not hesitate to use this filtration system on my aquarium.

Check the latest price of this filter on Amazon.

Maintenance & Cleanup

Just because a canister filter is big doesn’t mean you have to be concerned about it being a hassle! The HW304 b is one of the best-designed products I’ve come across for filter maintenance. The quadruple latching system is easily undone, as are the hoses that run from the top of the unit.

Once disconnected from your aquarium and opened, it’s a simple procedure to remove the media baskets for rinsing or replacement. The filter is somewhat heavy, so be careful when bringing it over to the cleaning area. This video allows you to see all of the details involved in taking apart this canister filter!

I strongly recommend not using tap water to rinse out your biological media compartments. Chlorine and chloramine are disinfecting agents added to tap water to kill bacteria. However, they aren’t selective and will kill the nitrifying bacteria that live in your media trays.

These bacteria are essential to ensuring your canister filter can detoxify ammonia, nitrite, and nitrate! A brief rinse to remove excess debris is okay, but no more than that.

Final Thoughts

I’m thrilled by this filter. It’s hard to find a canister filter that succeeds so well in so many categories. Spacious media baskets, excellent flow rate, and a sterilizer to further polish the water are a great menu of features for most aquarists keeping 150-gallon aquariums.

If your aquarium is under 100 gallons, I’d consider the Sunsun HW 302 Canister Filter for your filtration needs. The 265 gallons per hour flow rate is perfect for a mid-sized fish tank. And at 18W, the power consumption is also much lower. The other filter models I’ve outlined are also competitive and well worth using appropriately sized fish tanks.

Alternative Choices

Sunsun HW304 BFilstar XP-XLCobalt E-X-TEHEIM Ecco Pro 2236
Power UsageModerateModerateLowModerate
Water FlowModerateHighLowLow
Media CapacityHighHighLowModerate
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Filstar XP-XL

API is one of the largest and most trusted brands in the aquarium world. All of their products are quality, and the Filstar XP-XL canister filter is no exception. While the Sunsun canister filter is meant for a 150-gallon tank, the Filstar is rated for tanks up to 265 gallons!

The flow rate tops out at 450 GPH; you have the choice of adjusting it lower if your aquarium is smaller. The Filstar also includes four media trays for just as much customization. Both models are comparable in price, size, and power usage. However, the API Filstar also tends to run quieter despite the higher output motor.

Still, the UV sterilizer of the Sunsun canister filter is hard to pass up. Unless you absolutely need the higher capacity filtration of the API Filstar, the Sunsun remains an excellent choice for most tanks.

Cobalt E-X-T

If energy efficiency is most important to you, the Cobalt E-X-T is the unit I recommend above all others. At only 6W of power usage, it’s incredibly efficient for a high capacity canister filter.

However, low power use does come at a cost: this canister filter is rated for a fish tank 55 gallons or less in size.

While it’s not built into the filter, the Cobalt E-X-T also pairs well with the Cobalt Micro UV in-line water clarifier. That said, I still prefer having the bulb built into the filter for simpler fish tank maintenance.

EHEIM Ecco Pro 2236

Lastly, we have the EHEIM Ecco Pro 2236 as an alternative canister filter. While this unit is undeniably more power-efficient, this is mostly due to its lower flow. It has a max flow of 198 GPH, making it a fine choice for tanks no larger than 80 gallons.

Unlike the Sunsun canister filter, you can also adjust the flow rate as needed. The EHEIM Ecco Pro 2236 also has fewer media baskets than the Sunsun, meaning it’s not as customizable.

Bonus: Another popular alternative is the Fluval 406 canister filter.


I found that each of these models has strengths and weaknesses relative to the Sunsun canister filter. However, if you want a unit perfectly sized for aquariums 150 gallons in size, the HW 304B is hard to beat.

For 75-90 gallon aquariums the smaller Sunsun HW 302 Pro is hard to beat! While it doesn’t have the UV sterilizer of the larger HW304 B it does have a higher flow rate than either the EHEIM or Cobalt canister filters (265 GPH)! The HW 302 is also very competitively priced!

I hope you found this canister filter review useful! If so, feel free to send me a message letting me know how the Sunsun HW304 B Pro is working out for you!

Kelly Stanley