You guys are amazing, thank you for helping. I'm afraid I need to start with some very basic questions. I love pools, but I've never had one, and my understanding of them is little more than that they are a big hole filled with water. Much of the help above, as basic as I'm sure it is, is already beyond my education. I don't know what those things are or what components I need to make the pool operate. Is there an online resource on this site or elsewhere that can break the components down for me?
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We are planning a 20 x 40 concrete pool with a 4' shallow end and 9' deep end. No diving board, water features, or anything "extra" as the northern VA prices just for this are tapping us financially.

We know we want salt water because that's what people have told us is best, and honestly that's the end of our understanding. I understand that we need to determine our requirements and have each pool builder quote the same thing but I don't know what we need so I didn't do that.
I would be grateful for any additional wisdom you'd like to share!