Modular Filter Cup

Modular Filter Cup

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

Filter socks work, but cleaning them is one of those aquarium chores nobody looks forward to. Once they clog, you are pulling out wet, dirty socks, rinsing them, washing them, drying them, and keeping a rotation of clean ones ready.

The Stratiform Modular Filter Cup gives you a cleaner, simpler option. Use the sock opening you already have, load the cup with filter floss, pads, sponge, or bagged media, and when it gets dirty, swap or rinse the media instead of deep-cleaning a sock.

It does not remove maintenance completely, but it makes the messy part faster: the cup stays in the sump, and the media does the dirty work.

What You Can Put Inside

• Filter floss: Great for everyday mechanical filtration. Toss or replace it when dirty.
• Filter pads: Cut-to-fit pads can catch larger debris and fine particles before they settle in the sump.
• Coarse or fine sponge: A reusable option you can rinse and use again.
• Activated carbon: Use in a mesh media bag to help with water clarity, odors, and yellowing.
• GFO or phosphate remover: Use in a media bag when you want extra phosphate control.
• Ceramic bio media or bio balls: Adds surface area for beneficial bacteria.
• Specialty media: Use compatible aquarium resins or media bags according to the media manufacturer’s directions.

Tip: Loose chemical media like carbon, GFO, phosphate remover, or resin should go inside a mesh media bag so it stays contained in the cup.

Why Use A Cup Instead Of A Sock?

• Less sock washing: Replace dirty floss or pads instead of collecting a pile of used filter socks.
• Flexible filtration: Run floss by itself, sponge layers, a media bag under floss, or biological media depending on your setup.
• Easy to check: Lift the cup, look at the media, and change only what needs changing.
• Cleaner sump maintenance: Helps catch detritus, food, and particles before they break down in the sump.
• Reusable cup body: Rinse the cup as needed and keep using it.

Built For Aquarium Sumps

• Closed sidewalls: Helps direct water down through your media instead of letting it spill out the sides.
• Honeycomb floor: Supports floss, sponge, and media bags while allowing water to drain through.
• Black PETG: Durable 3D printed plastic with a clean look for sump use.
• Grip texture: Exterior texture makes the cup easier to handle with wet hands.

Build The Stack You Need

Each size family has four matching parts: a Top Section, 2 inch Cup, 4 inch Cup, and 6 inch Cup. Most setups start with one Top Section plus at least one cup section in the same size.

• Top Section: The support brim that sits in the sock holder.
• 2 inch Cup: Shallow option for tight spaces, low water height, or light media use.
• 4 inch Cup: Everyday depth for floss, pads, sponge, or a small media bag.
• 6 inch Cup: Deeper option when you want more media capacity.

The sections connect with a no-thread quarter-turn lock, so you can stack matching sections without fighting dirty threads.

Choose The Right Size

Choose the size that matches your sump or filter tray’s round filter sock opening.

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

Measure before ordering. Sump openings can vary, so match the product size to your actual sock holder.

Good To Know

• Sections are sold individually.
• Use matching size parts together. 2.75 inch, 4 inch, and 7 inch parts are not cross-compatible.
• Filter media is not included.
• Change or rinse media before it clogs and raises the water level in the cup.
• 3D printed PETG parts can show fine layer lines and small cosmetic variation.
• Rinse the cup before aquarium use.