It is a never ending problem of how to keep your hair from getting damaged by saltwater or chlorine from the pool. Here is the advices for this never ending problem. These advices are given in order of effectiveness.
The most efficient way to protect your hair is to soak it in oil. Oil is hydrophobic (waterhating) and will therefore keep the water, and thereby chlorine and salt, away from your hair. It also has the additional benefit that you get a deep conditioning treatment while having fun.
Another is to put lots of conditioner in your hair before going into the pool, that is for short stays, as the water will take the conditioner out of your hair. This also has the benefit of a deepconditioning treatment.
If you have forgotten either of these remedies, then make sure to soak your hair in fresh water, so it is saturated, which will hinder too much contact between chemicals and your sensitive hair. And make sure to pour fresh water over it again when you are done swimming.
All these remedies will be rendered even more effective if you purcase a competition swimmers swimcap, as the cap will keep the water away.
If your hair has turned green from chlorine, then dissolve two aspirins in lukewarm water and pour through your hair, keeping an extra bowl underneath, so it can be poured through a couple of times.
Swimming often means staying out in the sun, protect your hair from the sun by wearing a hat or use a hairproduct which contains a sunscreen.