Thank you for the reply,
We do not have a blanket on the surface of the water, I think we will be making that purchase. The hard cover fits well, and there was never any indication of heat loss at the edges. We are in the tub 1 or 2 times a week. I am not sure about a tier system...kwh has doubled (from what I remember on the letter, I will have to look back and check (Im not at home at the moment) We change the water every 6 months. Not sure on the filtering program (though I would guess it is at factory settings, I feel bad not knowing). As for cost, it has gone from about $65-$75 to $150. I expected the rate to go up in the colder months, but it is consistently higher every month, even in the summer when we dropped the temp to 100.