This was my first winter with chlorine, too, but we got a bit crazy with the warm NE weather and actually opened the pool up mid April. Same thing, looked great but just a slight greenish tint. I was a bit lax on my testing and maintaining after opening when the weather got cooler so I've been paying the price the past week or so (especially with the pollen being as bad as it was up here and some badly needed rain), with an emerald green pool. Been shocking and watching like a hawk, and now a very light "seafoam" color with some slight cloudy-ness, but you can still see the bottom. Hoping to have it almost crystal by this weekend for the holiday.