Osmosis in Fibreglass Pool: A Sign that your Pool Needs Renovation

REEF POOLS - Osmosis repair, fibreglass pool resurfacing

Osmosis is one of the worst issues that can happen with fibreglass pools. Popularly known as Black Plague, Osmosis is deterioration of top gel coat of fibreglass when air or contaminated water seeps through the pool’s lining, causing the pool surface to develop blisters which later cause algae growth inside the pool if cracked.


Reasons Why Your Fibreglass Pool Has Osmosis

There are a number of ways that can cause osmosis in your swimming pool, but are generally most of the black plague issues are related to age, pool’s quality, how it was installed, and how you maintain it.

#1. The Type of Materials Used

The quality of material used for manufacturing your fibreglass pool gel coat, coated laminate, and resin can affect the blister resistance of your pool.

#2. Faulty Techniques of Manufacturing and Construction

Most of the osmosis issues are due to the type and construction of laminate which is placed on the pool’s interior surface. Improper construction involves fibreglass pools coated with a cloth mat soaked in resin which may expose the pool to water saturation resulting in brownish black blisters.

#3. Maintenance

Maintenance or more likely lack of it can accelerate osmosis formation.

  • Raised exterior and water temperature (above 30°C) may make your pool’s coating porous and can make it more reactive towards chemicals which may elevate the rate of osmosis.

  • Secondly, excessive use of chlorine-based chemicals in water treatment weakens the coating surface, making it more prone to the formation of the black plague.


What are the Stages of Osmosis and How to Identify it

Usually, fibreglass pool problems like osmosis arise after 10-15 years. The development of osmosis in fibreglass pool is typically a slow process and occur in different stages.

Occurrence of Blisters

The formation of blisters or bumps is the earliest sign of fibreglass swimming pool osmosis. Due to age, faulty construction, low-quality material, or lack of maintenance, contaminated water from the outer surface of the pool permeates through the fibreglass layer and over time it creates thousands of air pockets between the fibreglass layer and top gel coat. These pockets continue to fill over time with moisture and air which makes the top gel coat to lose its flexibility, causing bubbles to breakout on the inner surface of the pool.

Formation of Algae

As the blisters age, they eventually crack and start leaking black/brown substance which forms algae inside the pool surface which is called the black plague.

Muddy or Contaminated Pool Water

The cracking of blisters brings in bacteria and dirt filled pollution to your pool water. If your swimming pool water is muddy or is dark coloured, it might be a sign of osmosis.

If your pool has the symptoms of any of the above deteriorations, it might be a sign of osmosis and a call for you to get professional resurfacing done.


The Need for Professional Resurfacing for Osmosis Correction