@Aero and @Dave K. Also thanks to John999. I just ordered ahh some from amazon. I have been corresponding with a different customer rep at Watkins and I finally got somewhere. After explaining everything that we have gone thru since day one with our 1.5 year old spa, the rep from Watkins is now on the same page with me. I sent him the link to this blog, and encouraged him to read it. We definitely had/have biofilms in our brand new spa, because one month in I experienced white flakes, which I had to skim off the top. It ended up being white mold. Our dealer was convinced I was in a CYA lock and had us drain the tub and start over. I know now that it was nothing I did wrong. I documented everything thru photos of the water, photos of test strips that were perfectly balanced except for no chlorine. My CyA has always been low, because I only supplement with MPS. I explained that I test for phosphates once a month, and keep this at zero by using phosfree. It has been an exhausting, nightmarish experience, so I am keeping my fingers crossed that ahhsome does the trick. 9 cartridges later, 3 xl vanishing acts, 2 ion sanitizers, 3 clean screen filters, and more test strips then I care to count.Watkins rep suggested I super sanitize with bleach. He recommended adding 4 cups before I drain in addition to purging with Ahhsome. Persistance and tons of research will hopefully pay off.