I suggest you find some other contractors who understand that "salt" means salt water chlorine generation (SWCG)--it's a chlorine pool, and ALL forms of chlorine are compatible with SWCG. It's not that hard to retrofit an SWCG system later, too. Picking the right and appropriate SWCG system does take some effort. I retrofitted an SWCG after 10 years and it works beautifully, and I still use other forms of chlorine as needed.
Nature 2 is, in the opinion of most of us, a waste of money that promises a lot and delivers very little. Nature 2 is quite secretive about its system and, for all of us, any company that's secretive about its chemistry has a reason to be, and not such a good reason. What it is is an erosion system that dumps traces of copper and silver into the water to kill algae. IT DOES NOT SANITIZE YOUR WATER! Its claim to reducing chlorine usage is based on the idea that if the Nature 2 kills the algae, you won't need chlorine to do it, therefore saving the chlorine to sanitize the water, using less chlorine. However, the replacement cartridges cost about $100/season and you can buy an awful lot of chlorine every year for that.
To REALLY confuse things, there are SWCG systems that incorporate a Nature 2 system into it! I personally don't recommend it.
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