A ran my previous 200 gallon tub on a Control-o-Matic SWCG (inline). The Taylor drop test kit for Sodium Chloride was helpful to confirm I was getting the target ppm and monitoring it over time as water was replaced with fresh due to splash out / carry out on suits / etc. Most SWCG will detect a low-salt or high-salt condition and flash an error light, but it is nice to know trends before they become a problem.
If you haven't read up on it yet, you will want to follow a modified version of Dichlor-the-Bleach method. I used Dichlor for the first week, then added the salt and turned on the SWCG. This ensured I had some reasonable amount of CYA (stabilizer) in the water to buffer the chlorine produced by the SWCG. I would also occasionally dose Dichlor as CYA drops over time. The SWCG can also cause pH to drift up over time, so one ends up adding acid from time to time.