4mm Acrylic Aquarium Tube Connectors (2pcs) — Straight, L, U & S Shapes

Route your air or CO2 line exactly where you want it — clean bends, no kinks, no clutter.

Tidy up the tubing in your planted tank with these clear acrylic connectors — rigid tube pieces that hold your 4mm airline or CO2 line in a fixed shape so it sits exactly where you place it. Hook a CO2 diffuser or drop checker neatly over the rim, turn a corner without a kink, or join two lengths of tubing inline. The transparent acrylic nearly disappears against glass, and unlike fragile glass lily-pipe fittings, acrylic won't shatter if it's knocked.

Why Aquascapers Choose These Connectors

• 🔍 Clear acrylic — near-invisible in the tank so nothing distracts from your scape
• 🛡️ Shatter-resistant — the safer alternative to fragile glass connectors
• 💧 Air and CO2 ready — works with diffusers, drop checkers, bubble counters, and air stones
• 🎯 Four bend shapes — Straight, L, U, and S to solve any routing problem
• 📏 Multiple lengths per shape — from tiny 4cm links to 30cm+ rim hangers

⚠️ Acrylic care: Acrylic is lightweight and won't crack like glass, but it scratches more easily. Clean with a soft cloth or sponge — skip abrasive pads and gritty scrubbers to keep it clear.

💡 Pro tip: For a floating drop checker or hang-in diffuser, pick a U-bend so the hook sits over the rim and the long arm holds your line at the depth you want.

Choose Your Shape & Size

Every option ships as a 2-piece set. Tube dimensions are the same across all shapes: 5mm outer Ø / 3mm inner Ø, sized for 4mm airline or CO2 tubing (compatible with 4–6mm line).

➖ Straight (inline coupler) — join two lengths of tubing end-to-end

• 10cm · 20cm · 30cm

📐 L-Bend (90° elbow) — turn a corner cleanly

• 4cm + 4cm (compact) · 4cm + 10.5cm · 4cm + 20.5cm · 4cm + 30.5cm

🪝 U-Bend (rim hook) — hooks over the tank edge, long arm runs down inside

• 4.5cm compact hook (1.5cm gap) · 4cm hook + 10.5cm arm · + 20.5cm arm · + 30.5cm arm

〰️ S-Bend (double hook) — hooks over the rim and redirects to hold gear at depth

• 12cm (5cm hooks) · 20cm (7cm hooks) · 30cm (7cm hooks)

Specifications

What's in the Box

• 2 × Acrylic Aquarium Tube Connector (shape & size as selected)

Pairs Well With

• CO2 Diffuser / Atomizer — the U-bend holds the diffuser line cleanly over the rim
• Drop Checker (CO2 Indicator) — hang it at mid-tank depth on a U- or S-bend
• 4mm CO2 / Air Tubing — the matching line these connectors are built for
• Bubble Counter & Check Valve — complete your CO2 delivery chain
• Air Stone / Air Pump — route air neatly from the pump to the tank

Your Top 5 Questions — Answered

1. What size tubing does this fit?

= It's built for 4mm airline or CO2 tubing and works with 4–6mm line. The connector tube itself is 5mm outer diameter and 3mm inner diameter — just slide your tubing over the ends.

2. There are so many shapes — which one do I need?

= Match the shape to the job: Straight joins two tubes in a line, L-Bend turns a 90° corner, U-Bend hooks over the tank rim so your line drops cleanly inside (ideal for diffusers and drop checkers), and S-Bend hooks over the rim and redirects to hold gear at a set depth.

3. Is it acrylic or glass?

= Acrylic. It's lighter than glass and shatter-resistant, so it won't crack if it gets knocked — a safer pick than glass lily-pipe connectors. The trade-off is that acrylic scratches more easily, so clean it gently with a soft cloth.

4. Can I use it for CO2, or is it only for air? 

= Both. The same 4mm line carries air or CO2, so these connectors work equally well for CO2 diffusers, drop checkers, and bubble counters, or for air stones and air pumps.

5. How many pieces come in a set?

= Every shape and size ships as a 2-piece set, so you've got a spare or enough for two runs of tubing.

Ships within 20–25 business days.