Overview

The custom sponge filter is built using parts likely already available for aquarium owners including ¼" airline tubing, o-rings, and rocks. Complete this low-cost build to have extra sponge filters that can be used for any aquarium including quarantine tanks.

Materials and Printing

We suggest using PETG since it is aquarium-safe. Black would be a nice color to use to blend in with other equipment. For the designer print profile, we have omitted unnecessary supports from the parts.

• Infill: 20%
• Walls: 3 (prevent water intrusion)
• Support: enabled (needed for hanging surfaces)

Assembly

Required Parts

• Filter Cap
• Air Lift Tube
• Air Diffuser
• Diffuser Cover
• Rock Box
• 4.5" of ¼" OD airline tubing (not including tubing attached from the filter cap to the air pump)
• 0.9" OD o-ring (optional)

1. Begin by filling the rock box with gravel larger than the gaps on the side of the box.
   
2. Insert an o-ring in the diffuser cover groove. This o-ring is used to ensure air does not leak out but is an optional addition.
   
3. Cut 4.5" of ¼" OD airline tubing and attach it to the air diffuser. The tubing should stick out as shown after the final assembly. Trim to appropriate length if necessary.
   
4. Complete the final assembly of the components as shown below. The airline tubing should be lined up with the bottom of the cap.
   
5. Once verifying everything fits, cut 3" diameter sponges with a 0.75" hole in the middle. The final thickness of the sponges should add up to 4".
   
6. All done!

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