Fibreglass pools

Fibreglass pools are becoming very popular

In recent times, fibreglass pools are becoming increasingly popular around the world. This is likely due to the low cost of installation, quicker installation and relatively low maintenance. Fibreglass pools will often require less acid to balance the pH and also are very unlikely to ever have black spot algae because of their smooth surface. Also, the surface is also popular as it is smooth on little hands and feet while swimming.

Fibreglass pools can cost less to build

In most cases, fibreglass pools are cheaper and quicker to build than concrete pools. This is because the time and materials needed to construct the pool is much less in the case of fibreglass. In short, this reduced time and effort translates into lower purchase costs for the buyer.

However, as the fibreglass surface ages, sometimes repairs are either very expensive or simply not possible.  This means that the entire structure of the pool may need to be replaced. So, in the case of a fibreglass pool, the new paint or gelocat fibreglass surface is hand applied. So this means that the new pool finish will not be as smooth as the original and will usually not last as long as the original factory coating.

“Fibreglass is a durable and smooth surface that is less expensive than other surfaces and is constructed much faster than other pool types”

Possible fibreglass gelcoat issues

If the water in not properly maintained, fibreglass pools can be prone to calcium formation and bleaching of the gelcoat. The calcium can be removed but bleaching of the surface is permanent. The best way to prevent this from happening is to maintain your water, especially the pH and Free Chlorine.  If either of these get too far out of balance then fading or bleaching can occur.  


Fibreglass surface with heavy calcium formation on the sides. Photo provided by

What causes fibreglass gelcoat fading or bleaching

Often this issue is only discovered by pool owners when the water level drops below its normal height. Fading or bleaching effect normally occurs when the water chemistry is out of balance. Most often it is very high chlorine levels for a period of time that is the main cause. In truth this does not happen very often but it does effect a lot of people.

Swimming pool covers can cause fibreglass to bleach

Remember, using a pool cover during the winter is a new experience for some pool owners. The most important thing to remember is that pool covers will dramatically reduce the amount of chlorine that you will need to keep the water clear. This means that when the cover is used in the pool that you should significantly reduce the chlorine output. This is because the cover will protect the chlorine in the water from UV light. This means that the chlorine in the water will last much longer than normal.

Finally, if the chlorine levels are not reduced then over the coming weeks the chlorine levels in your water can increase significantly. In these cases, the gelcoat of the fibreglass will fade due to excessive chlorine. This is a very common issue that fibreglass pool owners face. The key lesson is to test the water regularly, even when the pool is covered. The picture below was sent to us by a pool owner that left the chlorine of maximum output with a pool cover on while he was away on holidays for four months. When he returned home his pool was white. Fibreglass bleaching is not covered by manufacturer pool warranties.

calcium hardness in fibreglasss pool

Layers within a fibreglass pool

As the image below shows, the top layer of a fibreglass pool is actually quite thin, Because of this, it is a good idea to maintain the water regularly, Also, this will extend the life of the gelcoat and slow down the eventual fading of the surface. Remember, some newer fibreglass surfaces are not lasting as long as they used to years ago. This is yet another reason why maintaining the pool water is so important.

Gelcoat fibreglass pool


This graphic shows the approximate thickness of each of the layers of a fibreglass pool.

Renovating a fibreglass pool

When the time comes that your old fibreglass pool shell is too old and cracked to renovate, it will need to be replaced. In most cases, this is a huge expense and will damage the pool surrounds and landscaping. This is because the entire pool shell needs to be removed from the hole in the ground. In short, this means that you are left with nothing at all, except a huge hole in your backyard. At this point, you can either put a entirely new pool in the existing hole or you can fill it in. Basically, it means that your pool is essentially worthless and will cost you money to have taken out.

Remember, this is a downside of a fibreglass pool. On the other hand, it is very unlikely that the 200mm thick shell of a concrete pool will ever deteriorate to the point that it needs to be removed. As a rule, concrete pools can be completely renovated and have a new surface applied many times over many decades.

renovating fibreglass pools

The picture above shows a completed fibreglass pool shell being moved to the hold prepared for the pool.