Modular Filter Cup

Modular Filter Cup

Turn your aquarium’s filter sock holder into an easy, reusable media cup system.

Use the round sock opening already in your sump. Load the cup with filter floss, pads, sponge, or contained aquarium media, then swap or rinse the media when it gets dirty.

How to order

1. Measure the round filter-sock opening and choose 2.75, 4, or 7 inch.
2. Add one matching Top Section.
3. Add one matching 2-, 4-, or 6-inch Cup.

A matching Top Section is required and sold separately. Choose one Top Section and one cup depth in the same size.

Top Sections and cups are sold separately. Parts from different size families are not compatible. Filter media is not included.

What to put inside

• Filter floss: Replace it when dirty.
• Filter pads: Cut to fit the cup.
• Coarse or fine sponge: Rinse and reuse it as appropriate.
• Activated carbon: Keep it contained in a mesh media bag.
• GFO or phosphate remover: Keep it contained in a mesh media bag.
• Ceramic bio media or bio balls: Use pieces that remain supported by the cup.
• Specialty media: Follow the media manufacturer’s directions and use a media bag when required.

Media not included. Keep loose chemical media contained in a mesh media bag so it stays inside the cup.

Choose the right size and depth

Measure the actual round opening before ordering. Sump and filter-tray openings can vary.

• 2.75 inch: For 69.85 mm nominal filter-sock openings.
• 4 inch: For 95.0 mm nominal filter-sock openings.
• 7 inch: For 177.8 mm nominal filter-sock openings.

• 2 inch Cup: Compact clearance for tight sumps, low water height, or light media use.
• 4 inch Cup: Everyday depth for filter floss, pads, sponge, or a small media bag.
• 6 inch Cup: Extra depth when you want more media capacity.

Attach the cup

Align the downward chevrons, press the Top Section straight down into the cup, then turn it counterclockwise 90 degrees until the chevrons line up with the closed-padlock marks.

Built for sump maintenance

• Closed sidewalls: Help direct water down through the media instead of out through the sides.
• Honeycomb floor: Supports floss, sponge, and media bags while allowing water to drain through.
• Grip texture: Makes the cup easier to handle with wet hands.
• Black PETG: Durable 3D-printed plastic for aquarium sump use.

Cleaning and finish

• Rinse the cup before aquarium use.
• Change or rinse media before it clogs and raises the water level in the cup.
• Rinse the reusable cup as needed during normal sump maintenance.
• Fine FDM layer lines and small cosmetic variations are normal for 3D-printed PETG parts.