Nothing is more important for hot tub or spa water quality than your water filtering system, and so you are of course going to need to know how often to change hot tub and spa filters. One of the most important tips you should know when it comes to how often change spa filter is that you should set up a rotation cycle. You need to be cleaning your filter more often when you are using the tub more frequently, and do not have to worry about it so much during those times that you are rarely using the tub at all.