Thanks Watermom & PoolDoc! I have read all(?) the material over at the Pool Solutions site. Again, great info!

One other question for now: The vinyl liner, right above the water line, is rather dark gray and dingy. Using a brush or plain sponge on it has no effect. Is there a best practice for how to clean that? Any such thing as a "pool water safe" cleaner? Or do I just leave it alone?