Osmosis Treatment for Fibreglass Pools

Osmosis is a common issue that can occur in fibreglass swimming pools, caused by water penetrating through microscopic pores in the pool shell and reacting with uncured resins. This process forms blisters or bubbles on the pool’s surface, often filled with a vinegar-like liquid. If left untreated, osmosis can compromise the pool’s appearance and long-term durability.

The Osmosis Treatment Process

• Draining the Pool – The pool is completely emptied and allowed to dry.

• Inspection & Marking – All osmosis blisters are identified across the pool surface.

• Grinding & Removal – Each blister is ground back to remove the contaminated resin and expose clean, solid laminate.

• Drying Stage – The affected areas are left to thoroughly dry, ensuring no moisture remains trapped.

• Filling & Fairing – The ground-out sections are refilled with specialised fibreglass filler/bog to restore the smooth surface.

• Sealing/Barrier Coating – A waterproof epoxy or vinyl ester resin barrier coat is applied to prevent future water penetration.

• Resurfacing/Topcoat – Finally, a new top gelcoat, fibreglass laminate, or resurfacing system (such as ecoFINISH or paint) is applied to restore the pool’s look and ensure long-lasting protection.

Benefits of Proper Osmosis Treatment

• Stops further blistering and structural weakening

• Extends the life of the fibreglass shell

• Restores a smooth and attractive pool finish

• Provides a protective barrier against future osmosis issues

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