Ozone Detection Kit. Test how your hot tub's ozone generator is functioning, quickly and easily with the Spa Ozone Detection Kit from UltraPure. In just 3 easy steps, the spa owner will know if the ozone generator is working. If the ozone generator is producing sufficient levels of ozone, it will bleach the blue indicator material inside the glass tube to white. If the blue indicator material stays blue during the test, that means the ozone generator is not producing enough ozone. Three Easy Steps: 1. Turn the power off: Insert the Ozone Detection Tube inline with suction jet tube. 2. Turn the spa on for 30 seconds 3. If the complete detection tube went from Blue to White – Ozone is present.