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Fibreglass Pools

Many in ground pools in Australia are made of fibreglass. They age well but overtime can be subject to a range of issues.  The pool will generally have a fibreglass shell (made with resin and a glass fibre reinforcement) that’s about 5 – 10 mm thick with a smooth coloured gel coat on top. (inside of pool)

The general effects of aging fibreglass pools are: (mild to worse)
  • Some minor cracking
  • Worn areas
  • Stains
  • Blisters (Osmosis),
  • Algae difficult to control (Black spot)
  • Major cracks and leakage

As with all structures they need looking after so they continue to perform as designed and not fail catastrophically. By keeping the maintenance up this will go a long way to keeping it all together for the long run.

One of the worst things is to ignore minor issues and then let them become major ones which may then cost a lot to repair.

So if you see signs of:
  • Cracking,
  • Worn surfaces
  • Algae attack
  • Osmosis

Seek good advice as to how to deal with the matters at hand.

Generally cracking (minor) is the result of age or maybe settlement. Fibreglass pools are designed to flex somewhat (transport and installation mainly) Once in the ground, they are supported on a compacted sand base and the walls are back filled with compacted sand (hopefully well done).  They may get water underneath and hence flex when walking on the floor. Also it’s common to see flexing or movement at the steps once the sand has moved or washed away by ground water. These can lead to minor cracks or worse.

Worn areas may occur where the gel coat is thin and is subject to much foot traffic like on edges of steps, swim outs and maybe around some fittings or mechanical damage.

Stains are the usually the result of mineralisation (from pool water), pool chemicals, leaves, bottle tops.

Blisters (Osmosis). These often show up in fibreglass pools and much has been written about them. By way of summary they can be considered as pockets of moisture with in the layers of fibreglass and they (very) slowly migrate to the surface where they cause blisters. When these ultimately break they leave pocks (crevices) behind which fill with algae spores. The blisters can be several mm across to maybe 150 mm or more. Generally they look worse than they are but once broken can become an issue and should be attended too as water can get into the structure of the Fibreglass, not to mention allowing “blackspot” to develop.

Algae that is difficult to control is a result of poor water management and may often also be the result of Osmosis. Even if the pool surface (gel coat) was smooth at the time of construction, pool water chemicals, UV attack eat away at the surface. They create a pitted, creviced surface which is the ideal home for algae in all forms to take hold and thrive. Simply pouring chemicals into your pool will only knock the algae back, but not kill it as the roots are deeply imbedded in the damaged or blistered fibreglass.

Major cracks and leakage can be the result of pool settlement or movement. This is often observed in clay soils which when normally moist, then go through a drought, and thus compact (shrink back) and maybe take part of the pool with them. Also it can show up after the drought is broken when the soils swell unevenly causing stresses on the pool which it cannot resist as a whole and cracks in some places. An under pool water coarse may shift the sand base and allow for some settlement or local movement too.

The issues raised above can be difficult to understand or see when the pool is full, however if by careful observation you see some or all of these items seek good advice rather than leave them to fester.

Once any (or all) of the issues have been attended to then it would be a good idea to resurface your pool and a way to do this is using EPOTEC hi build epoxy coating. This will provide a smooth, long lasting, easy clean surface that will resist algae attack and be attractive for years.

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