I have found in my Hot Spring that by using the Ag+ in concert with ozone and dichlor will keep your spa very clean.
I have to travel quite a bit. I may go for a couple of weeks without seeing the inside of my spa. As long as I'm running with the silver and ozone, I'll come back to a crystal clear spa. I just make sure I boost the dichlor after I use it and then once every week or two to boost it.
Can't wait to hear what spa you buy. Be careful to not over analyze this purchase. It's good to research, but if you start doing too much, you may get too much information and get the ol' analysis paralysis. Have fun with this.
I really like the Sundance and the Hotsprings. It may come down to which dealer gives me a better deal. I also like both of those dealers. I spoke to a Caldera rep yesterday but got a bad vibe from him.
I think I am simply going to go wet test a Vita and decide between the Hotsprings, Vita, and Sundance. Price and satisfaction with the dealer/sales rep will be my guides as really, I seem to like themn all.
On a different note, I have ruled out Bullfrog not only because of the price, but also because it seems gimmicky.