Okay, I am new to the hot tub world, but have purchased a 2003 HS Sovereign and need to know what chemicals I need and if there is a good (less expensive) online option for purchasing these. I am about an hour away from the nearest dealer so need to be able to do as much as possible on my own. Also, I saw where specific brands are referenced. Are there less expensive subs that can be used or do I need to stick the specific brands noted? Thank you so much in advance!!