Overview

Sparging stones with stem-style connections can sometimes cause confusion because tubing dimensions are described using both inner diameter (ID) and outer diameter (OD). In certain filter‑style sparging stones, the tubing is designed to fit inside the stem, while in others the stem is designed to fit inside the tubing.

These different configurations are intentional, and understanding how the IDs and ODs relate ensures correct installation, secure connections, and proper sparging performance.

When the Tubing Inserts Into the Sparging Stone

In one common design below, the ID of the sparging stone stem matches the OD of the low‑pressure tubing.
This creates a snug, push‑fit interface where:

• Red lines (OD of tubing = ID of sparging stone stem) establish the insertion fit.
• Green line (OD of sparging stone stem) is larger than
• Blue line (ID of the low‑pressure tubing), meaning the tubing cannot fit around the stem.

This makes the connection “tubing‑into‑stem,” ideal for low‑pressure applications where secure engagement is needed without added fittings.
 

When the Sparging Stone Inserts Into the Tubing

In a second design below, the OD of the sparging stone stem matches the ID of the low‑pressure tubing.
In this case:

• Blue lines (ID of tubing = OD of sparging stone stem) show the stone stem fitting into the tubing.
• Orange line (ID of sparging stone stem) is smaller than
• Red line (OD of the low‑pressure tubing).

This creates a “stem‑into‑tubing” connection and is used when the tubing is meant to seal around the stone’s stem to ensure controlled gas delivery.
 

Why Both Configurations Exist

Both stem geometries are intentionally engineered to accommodate:

• Different tubing materials
• Low‑pressure versus moderate‑pressure gas delivery
• Specific sparging setups requiring insertion from one side or the other
• Minimization of leak paths
• Better mechanical stability depending on solvent, tubing, and orientation

The key is that ID and OD references are always relative to the type of connection the stone is designed for, not universal across all sparging stones.

Installation Guidance

To ensure correct fit:

• Confirm whether your system uses tubing‑into‑stem or stem‑into‑tubing design
• Inspect ID/OD markings on the tubing
• Check that the connection is snug without forced stretching
• Ensure that the fit is consistent along the entire inserted length

A proper match prevents leaks, ensures stable bubbling behavior, and avoids tubing pull‑off during sparging.