Bulkheads create a secure, watertight connection through the wall of an aquarium or sump, allowing plumbing to safely move water in or out of the system. These low-profile, reef-safe bulkheads are made from durable black ABS plastic and feature a slightly thicker construction than many standard aquarium bulkheads for added strength and reliability.
How Do I Pick the Right Bulkhead for My Project?
Threaded vs. Slip Connections
Bulkheads are available with either threaded or slip connections for attaching plumbing.
- Threaded: Threaded fittings screw directly into the bulkhead for a semi-permanent installation. Threaded connections make future plumbing changes easier, but they can sometimes increase the chance of a leak.
- Slip: Plumbing fittings or PVC pipe are glued directly into the bulkhead for a permanent installation. Slip connections are often the most robust option for long-term use.
What Size Bulkhead Do I Need?
When selecting a bulkhead, the hole in your tank must be slightly larger than the corresponding bulkhead’s “C” measurement, but no larger than the “A” measurement. See the diagram for reference.
Example: If your tank currently has a 1.75" diameter hole, you would want to use the 1" ABS Bulkhead.
Bulkhead and Glass Drill Bit Sizing Guide
Use the chart below to compare ABS bulkhead dimensions and match each bulkhead with the correct diamond-coated glass drill bit. Bulkheads are identified by the size of pipe they connect to—not by the larger diameter of the hole drilled through the aquarium.
The dimensions below apply to all slip & thread configurations.

| Bulkhead | A — Head Diameter | B — Full Height | C — Body Diameter | Hole Size | Glass Drill Bit |
|---|---|---|---|---|---|
| 1/2" ABS Bulkheads | 44 mm / 1.72" | 43 mm / 1.69" | 27 mm / 1.06" | 30 mm / 1.18" | 30 mm |
| 3/4" ABS Bulkheads | 52 mm / 2.04" | 50 mm / 1.98" | 34 mm / 1.33" | 35 mm / 1.38" | 35 mm |
| 1" ABS Bulkheads | 68 mm / 2.67" | 63 mm / 2.48" | 42 mm / 1.65" | 45 mm / 1.66" | 45 mm |
| 1-1/4" ABS Bulkheads | 77 mm / 3.05" | 71 mm / 2.80" | 51 mm / 2.00" | 53 mm / 2.09" | 53 mm |
| 1-1/2" ABS Bulkheads | 86 mm / 3.38" | 73 mm / 2.87" | 59 mm / 2.32" | 60 mm / 2.37" | 60 mm |
| 2" ABS Bulkheads | 98 mm / 3.85" | 73 mm / 2.87" | 72 mm / 2.83" | 75 mm / 2.96" | 75 mm |
| SKU | Bulkhead ABS Thread x Slip |
|---|---|
| Aquarium Type | Saltwater, Freshwater |
Product Questions
Unfortunately not, you would need to get a reducing bushing that we have in our sch 80 fittings.
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