It is 3' - 8', and yes that is gravel on the bottom before gunite. Don't know the reason why, but that is how they do them all around here.

Yes that is a heater, we hope to get and extra 2-3 months a year. Our neighbors close theres up at the end of October and open at the end of April.

Thanks for the yard comment, we are only 2 mile from the Appalachian Trail, not much flat land around here and we have view of the appalachian mountians from the front yard.

Your pool look great, looks like you will have plenty of decking. I have been following you construction thread.