Is it usual for my hot tub jet to turn on automatically even when im not using it?
they turn back stale after a while
Answers: Yes it is normal. As stated faster it is to circulate and filter the water. It is on a timer. The no brainer answer is the no brainer.
Yes this is a amazingly important portion of the system. They will turn on at intervals or when the heater kick on. This is required to circulate the water thru the pipes and pumps so it is ably mixed and does not become stagnate. I always generate sure the air valve are turned off when not using the tub as this allows it to circulate more faintly