I have only had it since May and the $30 includes only electricity. I assumed that my average electricity bill over the summer used to be around $30/month and now it is roughly $60. On a weekly basis I read my meter and calculate my total electricity consumption just to compare week to week to see if there is a problem. I haven't seen it really go up since the weather has been getting cooler. That could be because I just recently added the the bubble top and sealed the gap??
I just through the insulation in thick garbage bags and sealed them with duct tape. I know that garbage bags don't seem the smartest thing to use but I haven't had a problem yet. I just jammed them in and once i replaced the side board they kept in place. I also kept them away from the pumps.
As far as the jets blowing the bubble blannket off. Yes it did the first night but I now make a point of turning the top jets on the left side of the tub off before covering it and I haven't had a problem since.
My tub also arrived with cracked panels. I contacted Hydrospa and they sent me out the wrong ones twice. I now have enough skirting to go completely around my tub. It's good to know that Crown is their service rep. Before I bought my tub I called Hydro Spa a few times trying to find out who their rep was but they wouldn't tell me.