A pool light is only as watertight as its gasket. When the lens gasket becomes brittle, flattened, or cracked, water intrusion is no longer a possibility — it’s a matter of time. The Pentair 4” Lens Gasket (79108500Z) is a genuine OEM replacement designed to restore a proper seal between the light lens and housing, protecting the fixture from leaks, corrosion, and electrical damage.

This gasket is a critical safety and performance component for Pentair pool and spa lights. Over time, heat from the bulb, chemical exposure, and repeated servicing cause gaskets to lose elasticity. Reusing an old gasket after relamping or service is one of the most common causes of water entering the light niche. Replacing it with a new OEM gasket ensures the light remains sealed as designed.

At Benchmark Pool Supply, this gasket is recommended anytime a Pentair light lens is opened — not just when a leak is already visible.

Why Pool Light Lens Gaskets Fail

Pool light gaskets operate in harsh conditions. They are constantly exposed to heat cycles, chlorine, salt, and pressure from being submerged. Even if a gasket looks “okay,” it may no longer compress evenly, allowing slow leaks to form.

Once water enters the light assembly, it can damage the bulb, socket, wiring, and even trip breakers or GFCIs. The Pentair 79108500Z lens gasket prevents these issues by restoring the original factory seal between the lens and the fixture body.

OEM Fit for Pentair Pool and Spa Lights

This 4-inch lens gasket is manufactured to Pentair’s exact specifications for thickness, diameter, and material composition. Proper gasket compression is essential — too thin and it leaks, too thick and the lens won’t seat correctly.

Aftermarket gaskets often vary slightly in size or rubber compound, increasing the risk of leaks. Using a genuine Pentair gasket ensures proper fit, correct compression, and long-term reliability.

Common Applications and Use Cases

The Pentair 79108500Z lens gasket is commonly used during:

• Pool or spa light bulb replacement

• Fixture servicing or inspection

• Leak repair or preventative maintenance

• Seasonal maintenance on older light assemblies

Replacing the gasket during service is considered best practice and helps prevent costly electrical repairs down the line.

Installation and Service Considerations

Installing a new lens gasket is straightforward but must be done carefully. The gasket should be seated evenly and free of twists or debris before tightening the lens clamp or screws. Over-tightening should be avoided, as it can distort the gasket and compromise the seal.

Once installed, the fixture should be inspected for proper seating before being returned to the niche.

Product Specifications

Buy with Confidence from Benchmark Pool Supply

When you purchase the Pentair 4” Lens Gasket (79108500Z) from Benchmark Pool Supply, you’re buying a genuine OEM electrical safety component from a pool supply company that understands lighting systems and proper service procedures. We stock authentic Pentair parts, verify compatibility, and stand behind what we sell. Whether you’re servicing a customer’s pool or maintaining your own, you can trust you’re getting the correct gasket backed by real expertise.