How often your tub is used and the number of people using it will dictate how often you should have it drained. Pros drain all the water, clean the tub and its parts, clean the filter, and ensure optimal health. A typical homeowner who uses their hot tub occasionally might drain the tub 2-5 times per year, while someone who is having nightly hot tub parties with 10 or more people in the tub might have to get it drained once a month or more. Draining costs depend on the company, the size of the tub and other factors. Here is one example of cost:
Hot tub draining: $125 from Dolphin Pool Maintenance.
Typically provides a filter cleaning at the same time.