I used what I thought was very little Dichlor while I had the Eco One working, but several posters chimed in that they thought I was over doing the Chlorine.
My tub stayed absolutely fine, I was able to go longer than the usual water change interval, and my skin felt nice and soft. I liked the subtle fragrance - Coconut if I recall - and overall it seemed to work just fine.
It is a complete system - you have to do a purge first, then drain and then begin the program. The pH tends to go a bit high and stay there, and I fought to drop it. The Eco One folks told me to leave it there, around 8.0 I think. I did, and it was much less work once I gave up on that point. I did not see any calcium buildup while the pH was that high, which is unusual.
I went back to Dichlor after using up all the stuff in the start-up kit which was very kindly supplied to me. I liked it, but I have been using Dichlor successfully for close to 25 years and old habits die hard.
I am currently on Brilliance, which I like as well. I need the feeder right now as I recuperate from a back injury and back surgery. But I like the Brilliance well enough that I might change to it ongoing. I sell Brilliance in my store, so it is easy to just grab what I need when I need it - I do not sell Eco One currently.
8-)