Quiet Outlet Diffuser for Rear-Filter Aquariums

A slotted box that sits on the end of the filter return hose in a corner of the tank. Water leaves through 51 times the hose area, slowly and quietly, and a snail on one face cannot block it.

A loose return hose splashes, and if a snail sits on its end it can spray water out of the tank. This diffuser takes the hose in a socket on its back face and lets the water out through slotted faces on the other sides. The outlet area is about 51 times the hose's, so the water leaves at around 1 cm/s at 150 L/h. Glued into a corner: back face on the divider glass, solid side on the side glass. The lower slots are under water (quiet); the top slots ripple the surface.

What it fits

• Hose with an outside diameter of 9.6 mm (socket bore 10.2 mm, slide fit).

• Hose centre about 26 mm from the side glass.

• Two files: side glass on the right or on the left.

What you need

• PETG filament.

• Aquarium-safe silicone.

Print settings

• Material: PETG

• Nozzle: 0.4 mm (ours was printed with a 0.6 mm nozzle)

• Layer height: 0.18–0.2 mm

• Walls: 3–4

• Infill: any

• Supports: None: they would end up inside the box.

• Orientation: Back face (the one that glues to the divider) down.

• Bed: Fits A1 mini / 180 mm beds. 42 × 40 × 55 mm.

Files

• outlet-diffuser_glass-right_hose9.6.stl — side glass on the right

• outlet-diffuser_glass-left_hose9.6.stl — side glass on the left (mirror image)

Fitting

• Push the hose into the socket dry: it should go in with a firm push.

• Silicone on the back plate and on the solid side, press into the corner with the hose in.

• Leave the silicone to cure for 24 hours before the water goes back.

Limits

• Fixed size: other hose diameters will not fit the socket.

• Hangs 40 mm below the opening; set for a water line close to the opening.

How it was checked

Printed and in use: we printed this design (the side-glass-right file) and it is siliconed into our own tank. The left file is its exact mirror image.

Safety

• Use PETG and aquarium-safe silicone only.

A parametric version of this part is on mislastudio.com: https://mislastudio.com/m/distribuidor?utm_source=printables&utm_medium=free_model&utm_campaign=distribuidor

Designed by Misla, a small studio of engineered 3D-printable parts: https://mislastudio.com/?utm_source=printables&utm_medium=free_model&utm_campaign=distribuidor