SunSun HW-304b Aquarium External Canister

The SunSun HW-304b Aquarium External Canister is a powerful external filter for larger aquariums. It provides mechanical, biological and chemical filtration through four media baskets. In addition, it has a built-in 9W UV sterilizer to help improve water clarity.

The SunSun HW-304b has a maximum rated flow of 2,000 litres per hour (L/h). Therefore, it provides strong water circulation while moving aquarium water through the filter media. Actual flow may be lower once hoses, filter media and installation height add resistance.

The filter has a rated pump power of 55W and a maximum delivery height of 2.5 metres. It also includes a separate 9W UV sterilizer.

Yes. The SunSun HW-304b Aquarium External Canister includes a built-in 9W UV sterilizer. The UV system can help control free-floating algae and microorganisms that pass through the unit. As a result, it can support clearer aquarium water.

The HW-304b has four filter media baskets. This gives you plenty of space to arrange different filter media for mechanical, biological and chemical filtration.

You can customise the four baskets with suitable aquarium filter media. Common choices include filter sponges or pads for mechanical filtration, ceramic rings or bio balls for biological filtration, and activated carbon or other specialist media for chemical filtration.

Arrange the media according to the direction of water flow and the needs of your aquarium.

Yes. The filter works well with freshwater aquariums, including tropical tanks, planted aquariums, cichlid tanks and other larger setups. Its large media capacity also gives you flexibility when choosing filtration media.

Yes. The SunSun HW-304b is suitable for both freshwater and saltwater aquariums. However, regular cleaning and maintenance are important, especially when the filter is used in a marine system.

Published recommendations vary significantly by seller, with some listings suggesting around 150 gallons (about 568 litres) and others giving different capacities. For that reason, I would avoid promising a universal maximum tank size in the FAQ.

The right filter size also depends on fish load, aquarium type, filter media and required turnover. A heavily stocked aquarium usually needs more filtration than a lightly stocked tank of the same volume.

Yes. Its 2,000 L/h rated flow, four media baskets and large canister design make it a strong option for larger aquarium systems. However, always match the filter to your tank volume, fish load and desired water turnover.

The HW-304b is designed as an external canister filter, so the motor and filtration chamber remain outside the aquarium. Correct installation and proper priming help keep operation smooth.

If the filter becomes unusually noisy, check for trapped air, blocked hoses, dirty media or debris around the impeller.

Yes. The HW-304b has a manual priming pump that helps start the siphon and fill the canister with aquarium water. This makes initial setup and restarting after maintenance easier.

There is no single cleaning schedule for every aquarium. Instead, check the filter regularly and clean it when water flow begins to drop or excess dirt builds up.

Heavily stocked aquariums may need more frequent cleaning. Meanwhile, lightly stocked tanks may run longer between maintenance sessions.

Avoid replacing or aggressively cleaning all biological filter media at the same time. This helps preserve beneficial bacteria.

Rinse reusable biological media gently in old aquarium water during a water change. This helps remove loose waste without exposing the media to chlorinated tap water.

Mechanical pads and sponges can be cleaned or replaced when needed. Chemical media should be replaced according to the instructions for that specific product.

Yes. One of the four baskets can hold activated carbon or other suitable chemical filter media.

However, activated carbon is optional. You can instead use the available basket space for extra biological or mechanical filtration, depending on your aquarium.

Yes. Ceramic rings and bio balls are suitable biological filter media for the SunSun HW-304b. Their surfaces provide space for beneficial bacteria to grow.

For best results, combine biological media with good mechanical filtration so that large amounts of dirt do not collect on the biological media.

Not necessarily. The UV sterilizer can be used when extra water-clarity support is needed. However, how long you run it will depend on your aquarium and the reason for using UV.

Also, switch the UV system off when using treatments if the medication instructions recommend doing so.

No. The 9W UV sterilizer is an additional water-treatment feature. It does not replace mechanical or biological filtration.

The four media baskets perform the main filtration work, while the UV system targets organisms suspended in water as they pass through the unit.

Reduced water flow can be caused by:

• Dirty filter pads
• Blocked filter media
• Kinked hoses
• Dirty inlet pipes
• Debris around the impeller
• Trapped air
• Incorrect priming

First, unplug the filter. Then, check the hoses, intake, impeller and filter media for dirt or blockages.

The SunSun HW-304b Aquarium External Canister combines a strong 2,000 L/h rated flow, four large media baskets and a built-in 9W UV sterilizer. Therefore, it offers flexible mechanical, biological and chemical filtration in one external system.

For customers who want a powerful external aquarium filter with plenty of space for custom filter media, the HW-304b provides a practical all-in-one filtration solution.

The published specification is approximately 290 × 290 × 485 mm. Because installation also requires room for hoses and maintenance access, leave extra space around and above the canister.