Welcome to our forum.
When I goggle Solana SX. Hot Spring comes up and the model is on their website. The owner said is was made by Watkins but not sure what year. On the website it says it seats 3 people and the picture on the ad looks like the one on the Hot Spring website. My husband is going to try and go look at it today (I have to work).
If you want less chemical, have you thought of trying hydrogen peroxide? I have to be totally honest in that we don't yet have a spa as we just ordered our first hot tub yesterday. We have been in a friend's spa however and they use hydrogen peroxide. Was a totally different experience being in that tub. Skin felt silky smooth, no chemical smell, etc., etc. My wife has chemical sensitivities and this is what we are going to try when we get our spa. When we spoke to our dealer about it, the only thing they had against it was that the hydrogen peroxide was not long lasting and he said that you had to "stay on top of it". Once again, I don't know all the ins and outs, but I can say for certain that being in our friends tub with hydrogen peroxide was a very unique and pleasant experience.