Despite popular opinion, I rely upon the SWG to tell me what the salt level is (actually its amps). The reason is quite simple, the SWG will turn itself off it the amps are too high or too low. So by relying upon the SWG to tell you salt level, you are really letting it tell you what is right. I use salt strips and a drop kit as well but it really doesn’t matter what those read. It may be useful as a life test for the SWG since the salt reading error does tend to increase with age. But bottom line, what the SWG thinks is very important and what the actual salt level is is less important.
Personally, I target the low end of the SWG range but that is to reduce the false high salt errors when very hot water travels through the SWG after solar is turned on. Amps increase with water temperature and if the salt level is too high, hot water can trigger an alarm.
While it is true that an SWG will produce more chlorine at higher salt levels, this does not mean that the life of the SWG is extended with higher salt levels. SWG life is usually measured in amp-hours. With higher salt levels, the amps increase and chlorine production increases in proportion to the salt level so the run time can decrease by the same amount (visa versa for lower salt levels). So in reality, the life of the cell should be nearly the same with high or low salt level as long as the levels are within range of the SWG operating parameters.
As a SWG ages, you will find more salt is required to prevent low salt errors at which point it is a warning that the cell is about to die and you need to start shopping for a cell.
So long story short, I don’t think it matters much what the salt level is as long as the SWG thinks it is within normal operating range.
Also, forgot to add that yes, a SWG is a TDS meter. However, some offset the TDS measurement to account for typical levels of other solids.
