Fiberglass Pools
With so many fiberglass pools on this beach, we have done the research on how they need to be maintained. We cannot reverse gelcoat damage. We can stop it before your whole surface is gone.
What is actually happening
The gelcoat is the hard finish you touch, and it is remarkably tough. There is really only one thing that beats it: the combination of high pH, high chlorine and calcium arriving together. Any one of the three is manageable. All three at once is what takes a fiberglass pool apart.
Did your pool service let your fiberglass pool turn green over the winter, then show up in the spring with a granular chlorine called CalHypo to clean it?
Look at what that product actually is:
He just created the perfect storm.
When your pool water is low, are you seeing the gelcoat turn white?
The perfect storm creates calcium silicate, which is itself a type of glass. It is white, and it does not simply sit on top of the surface. It binds to the gelcoat and breaks the chemical bonds that make the gelcoat what it is.
This is the part that surprises people. Acid takes ordinary scale off without much trouble, so when it does not touch this, the assumption is that the surface is simply worn out. It is not. Acid will not remove calcium silicate, because it is glass.
How we prevent it
The obvious answer would be to run the pool with no calcium at all, and that answer does not work. It is not possible to hold an LSI balance without calcium, and water that is not LSI balanced causes its own set of problems. The calcium has to be there.
What we can do is take it out of the reaction. Chelating the calcium once or twice a year keeps it locked up and unavailable, and holding the other two legs of the storm in the right place means the reaction never gets started.
Kept low rather than removed, and chelated once or twice a year so it stays tied up instead of available to react with the surface.
Higher than most people expect, and deliberately so. Combined with balanced water it keeps the pool comfortable and protects the finish rather than attacking it.
Enough to keep the water sanitary and meet the oxidation demand, without the sustained high chlorine that makes up the third leg of the storm.
Those three together break up the perfect storm. None of them is exotic or expensive. They just have to be held there every week, which is the entire difference between a service that tests your water and a service that manages it.
Check your own pool
Run your hand along the wall about a foot below the waterline. If any of these are true, the reaction has already started, and it is worth having the water looked at now rather than next season.
Being straight with you about this: what has already happened cannot be undone. There is no chemical that puts a gelcoat back. What every week from here decides is whether it stops where it is, or keeps going until the surface comes off white on your hand across the whole pool.
The math on waiting
There is a company that will gladly come out and resurface your fiberglass pool, and they do good work. It costs roughly ten thousand dollars, and once the surface is new the exact same water will start taking it apart again.
Prevention is not a product we sell you. It is what correct weekly water balance already does.
What prevention actually is
If it is a rental
This is the part owners tend to find out from a review rather than from an inspection. Chalking transfers onto hands and swimsuits, and a guest who comes out of the pool with white residue on a dark swimsuit describes the pool as dirty, not as chemically imbalanced. The pool can be perfectly sanitary and still cost you the booking.
A fiberglass pool in a rental program is worth staying ahead of for the same reason you stay ahead of the HVAC. It is not the repair bill that hurts most, it is the season of reviews you get before you fix it.
Have a fiberglass pool on the beach?
Tell us your town and roughly how old the pool is, and we will tell you honestly whether this is a chemistry fix or a surface that is already past saving.
