What it does
The downstem is the path smoke takes from the bowl into the water. Its tip sits under the water line, so every hit bubbles. A diffused downstem has several slits at the tip that split the smoke into smaller bubbles; an open-end downstem has one opening and pulls with less resistance.
Fixed vs removable
| Fixed (welded in) | Removable | |
|---|---|---|
| How it looks | Part of the bong; only the bowl comes out | Slides into the bong's joint; the bowl slides into it |
| Pros | No leaks, no extra joint, sturdy | Replaceable if it breaks or clogs; easy to clean |
| Cons | Harder to clean; a crack means the whole piece | Must match size exactly |
How to measure a removable downstem
- Joint sizes. A downstem has two: the top, which goes into your bong (usually 18mm or 14mm), and the opening that takes your bowl (usually 14mm). These are written as "18/14" or "14/14." Most standard beakers use 18/14.
- Length. Measure from the bottom of the frosted joint at the top (the part that seats in the bong) to the tip. Common lengths run from 3 to 6 inches, in half-inch steps.
- Check fit. The tip should sit about 1/2 inch above the bottom of the base, so it is well under water without touching the glass.
Measuring the bong instead? Measure from the top of the bong's joint to the bottom of the base, inside, then subtract about 1/2 inch.
Diffused vs open-end
- Diffused (slitted): more, smaller bubbles; cooler feel; slightly more drag; slits need cleaning.
- Open-end: fewer large bubbles; easiest pull; easiest to clean.
If your bong has a percolator, an open or lightly diffused downstem is usually enough.
Common mistakes
- Ordering by bowl size only. The top joint has to match the bong too. Check both numbers. See what size bowl fits my bong.
- Too long. A downstem that touches the bottom can crack the base or block airflow.
- Too short. If the tip barely reaches the water, you need to overfill the bong. See how much water to put in a bong.
- Stuck downstem. Do not force it. Soak the joint in warm water, then twist gently.
Pro tip
Downstems collect the most residue in the whole bong. Pull and soak it in a zip bag with isopropyl and salt every time you clean the bong; a clean downstem pulls noticeably easier.
