You can run a bromine pool with an SWG and the chlorine produced by the SWG will convert to bromine, provided you have an adequate bank. Since bromine can't be stabilized against sunlight it will break down quickly, putting a lot of strain on the SWG to keep up.
I would personally just dump the water and start fresh. Getting an SWG pool up and running from scratch can be really easy. The important thing would be to test with an adequate kit, TF-100 or k-2006c, and get your chemical levels in line with the TFP recommended levels. The TA and CYA levels we recommend especially help keep things trouble free in a salt pool. SWG pools are not "set and forget", but with regular testing they can be extremely easy to maintain and keep the water consistently clear with minimal work.