Hi all. I had a big issue with Goldline (now Hayward) when we first started installing their units a few years back, about the higher cya level. There is apparently nothing inherent in the SWG which would require twice as much cya as a pool chlorinated in other ways. However, they all seem to call for a higher cya level. (Actually, after a few 'heated' discussions, I'm supprised they still answer my calls )
As I see it; salt will only leave the pool by backwashing or splashout. Similarly, cya isn't going anywhere the salt doesn't go (niether will evaporate with the water). Therefore, I present "Waste's Best Guess Chart For CYA in a SWG Pool":
*** For every 100 lbs salt added, add 1 lb cya***
This will get you 30-40 ppm cya ( for systems that opperate on a 2600 - 3400 ppm salinity) Keep your cl ~ 2.5 - 3 and you should not experience problems!