The test itself is not special. The hard part is understanding what is connected. Once the circuit is mapped and isolated, this is the same as any other line pressure test.
Why Split Skimmers Confuse Testing
A split-skimmer setup may include two skimmers, shared suction plumbing, a shared equalizer line, a main drain tie-in, diverter valves, hidden crossover plumbing, an abandoned equalizer line, or an unknown capped fitting. If one opening is missed, pressure bleeds into another connected path -- the gauge drops, and the technician misreads a false failure as an underground leak.
What to Identify Before Testing
Pre-Test Mapping Checklist
- Number of skimmers on the pool
- Number of ports in each skimmer body
- Which port is the suction line
- Which port is the equalizer connection
- Whether a float valve or diverter is present in any skimmer
- Whether the main drain is tied into the skimmer circuit
- Whether the second skimmer connects to the same plumbing
- Whether the equalizer is active, capped, or abandoned
- Whether any line connects to a wall fitting or secondary drain
Do not assume the ports are standard. Older installations, renovations, and non-standard builds can have unexpected connections. Trust what you can physically trace and confirm -- not what a label says or what the customer remembers.
Check the Skimmer Body First
Before interpreting a test result as an underground pipe problem, inspect and dye test the skimmer body itself. The skimmer is often the leak -- not the line. Check for skimmer throat separation, body cracks, separation at the tile line, bad joints around the mouth, a leaking equalizer fitting, a leaking suction port, and poor plug seal condition. A leaking skimmer body will mimic a failed line on a pressure test.
Normal Pressure Test Logic Once Isolated
After the circuit is mapped and every opening is sealed, the pressure test logic is the same as any other line. The technician confirms that all openings are sealed, plugs are holding, the test setup itself is not leaking, the correct circuit is isolated, and the gauge result is repeatable. A pressure drop on a properly isolated circuit means that circuit did not hold. If the circuit was not fully isolated, the result cannot be interpreted.
A pressure drop is a clue, not a conclusion. Verify isolation before declaring an underground pipe failure.
The H.U.N.T.E.R. Method Applied
This is an Understand problem before it is a Test problem. If the technician does not understand the skimmer configuration, the pressure test can produce a false result.
Ask whether two skimmers are present, whether they share plumbing, and whether any work has been done on the skimmers.
Map every port and connection before touching a plug. Know what connects to what.
Dye test the skimmer body and throat first. Rule out surface leaks before pressure testing the line.
Plug all confirmed openings. Verify each plug. Apply controlled pressure to the confirmed isolated circuit.
If the line drops, the evidence is a failed isolated circuit -- not yet a located pipe break.
Report which circuit failed, which were not tested, and what the next diagnostic step is.
The number one false positive in pressure testing comes from missed connections. A technician plugs one port, applies pressure, sees a drop, and calls it an underground leak. They drive away and tell the customer they need excavation. But they left the equalizer line open.
Map before you plug. Trust the trace, not the label. Dye the skimmer body before you blame the plumbing. That is what a trained technician does differently than someone who just has the equipment.
Once the circuit is genuinely isolated, the test is simple. It is everything before the test that matters.
Beginner vs. Advanced
Beginner Focus
- Map all ports before testing
- Do not trust old labels
- Dye test skimmer body and throat first
- Verify every plug seal
- Do not call a false drop an underground leak
- Document unknown connections
Advanced Evaluation
- Shared skimmer manifold layouts
- Main drain tie-in behavior
- Abandoned equalizer line tracing
- Commercial skimmer configurations
- Camera or sonde confirmation
- Hidden crossover plumbing
Common Mistakes
- Plugging only one skimmer port and missing the equalizer
- Missing the second skimmer connection entirely
- Missing a main drain tie-in to the skimmer circuit
- Trusting a float valve or diverter as an adequate pressure seal
- Ignoring the skimmer throat and body as leak sources
- Not verifying that plugs are holding before reading the gauge
- Calling a false pressure drop an underground pipe break
- Making this sound more complicated than it is -- the test is normal once isolated
Frequently Asked Questions
Is there a special test for split skimmers?
No. Once the circuit is properly mapped and isolated, it is the same pressure test used on any other pool plumbing line. The special work is in the mapping -- not the test procedure itself.
Can a float valve in the skimmer be used as an isolation plug?
No. Float valves and diverters are not rated as pressure seals. They can pass water or air under test conditions. Always use proper expansion or threaded plugs and verify they are holding before reading the gauge.
What is an equalizer line and why does it matter?
An equalizer line connects the bottom of the skimmer to the pool to allow the pump to draw water when the surface drops below the skimmer mouth. If this port is open and unpluggged during a pressure test, the test circuit is not isolated and the gauge result is invalid.
What should be done if a connection cannot be identified?
Do not test. Document the unknown connection, photograph it, and note in the report that this circuit could not be fully isolated. Proceeding with an unconfirmed isolation produces a result that cannot be interpreted. A camera or sonde may help trace the unknown line.
Learn to Map Before You Plug
The H.U.N.T.E.R. Method course covers pressure testing logic in full -- including how to identify, isolate, and verify circuits before reading any gauge.
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