Blue Pet BLH-401 Aquarium Hang on Filter 4 watts

The Blue Pet BLH-401 is a 4W hang-on-back (HOB) aquarium filter delivering up to 250 L/H, a compact, quiet filter that hangs on the rim to keep small tanks clean while saving space inside the tank. It removes debris, food residue and particles for clear water, creates a gentle oxygenating waterfall, and installs in seconds — a simple, efficient HOB for small community and betta setups.

Why choose the Blue Pet BLH-401?

• 250 L/H flow from an efficient 4W motor.
• Hangs on the rim — keeps the tank interior clear.
• Waterfall return that oxygenates the surface.
• Mechanical + biological filtration via the cartridge.
• Quiet and easy to maintain.

Specifications

Which tanks is it best for?

With 250 L/H, the BLH-401 suits small tanks up to roughly 60L. For a smaller option see the BLH-301 (180 L/H); for more flow, the BLH-403 (500 L/H). Learn the format in canister vs HOB vs sponge.

How to set it up

Hang the filter on the back rim, prime it if needed, and plug in. Keep it running 24/7, and rinse the cartridge in old tank water (never tap water) when flow slows. See how to install an aquarium filter.

Frequently asked questions

What size tank is the BLH-401 for?

Small tanks up to roughly 60L, based on its 250 L/H flow.

Does it oxygenate the water?

Yes. The waterfall return improves surface oxygen exchange.

Is it betta-friendly?

It is gentle, but if flow is too strong for a betta see how to reduce filter flow.

How do I maintain it?

Rinse the cartridge in old tank water when flow drops, usually every 2–4 weeks.

Should it run all the time?

Yes, keep it running 24/7 to protect the beneficial bacteria.

New to filtration? Read our complete aquarium filter guide and types of aquarium filters.