I'm pretty sure those hi Chlorine levels are for isolated spas that stay hot all the time, and have a high bather load.

I keep my spa the same as the pool.. there is a pool return for a "fountain" that feeds the spa (overflow) so it always has a fresh supply of CL. I usually don't check the SPA.

Actually, currently my SPA fountain is plumbed to my solar heater, so the SPA doesn't get constant CL. I've programmed my computer to start the filter pump and run in "spillway" mode (suck from pool, dump to spa) for 30 minutes. It takes me 15 minutes to fill my spa, so that 30 minutes is pretty much a total water change daily.

Robert