I'm not familiar with cartridges but you can buy an aromatherapy canister (hot tub warehouse online has them) in which you put aromatherapy beads whichare available many places (such as spa depot). Yo ... read more
Very positive experience. I was kept informed of when work would be done, they kept to a time schedule, resolved issues quickly, and they cleaned up and left things in order every day. Quality of workmanship is top notch.