I love a nice hot bath, especially with a good book and some powerful jets. My problem is that I get sick to my stomach thinking about the gunk that builds up in the jets--you know the parts of the jets that you can't get at.
Here's the solution.
Fill the tub with hot water to about 3 inches above the jets. Add 1 cup of bleach and a couple of tablespoons of powdered dishwasher detergent. Run the jets for fifteen minutes. (Our jets just have one speed, but if your jets have more than one speed, use high speed.)
Try not to get sick if your water ends up with nasty particles in it. Just pat yourself on the back for getting rid of them.
After fifteen minutes, drain the tub and fill it with cold water to about 3 inches above the jets. Now run the jets for ten minutes.
Drain the tub and rinse it out well.
It's recommended that you do this about once a month, but I suppose it depends a little on how much you use your jetted tub. Every other month is probably good enough for a lot of us, but I once heard that Oprah takes a long jetted bubble bath once or twice a day. She might need her people to clean hers more often.