I found the cover top not thick or tight fitting enough for our winter and was able to replace it with Thecoverguys.   Challenge was getting the correct size, as it is not provided in manual and an odd size.  I had to create a template and mail it to them.   I find with my new cover I use much less energy!  You can also turn some jets off by simply turning them, which results in stronger pressure.   I am really thrilled with the hot tub!