There are plenty of spa owners at poolspaforum.com who use the Dichlor-then-bleach method (Dichlor used initially for about a week to build up CYA and then switch to bleach) and are able to keep their pH and TA fairly stable by having the TA be low (usually 50 ppm or a little lower), using 50 ppm Borates, and not trying to keep the pH much below 7.8 though some find the pH to be OK in the 7.5 to 7.7 range. Now keep in mind that these are residential spas so typically not used more than once a day. The water stays in good shape for about twice as long as Dichlor-only users (probably due to CYA build up making chlorine less effective). I would not characterize them as cesspools though it is true that they build up some organics that are not fully oxidized but the only indicator of that is a slowly increasing chlorine demand from around 25% per day to 50% per day. Ozonators are a mixed bag, but for high-use spas they help while for low-use spas they mostly just increase chlorine demand.