Hi Jonny;

Janet (aylad) is right that baking soda doesn't increase your salt (chloride) levels, but . . .

The problem is, you may not be measuring salt! If you are going by the 'salt meter' built into your SWCG, or if you have a salt meter, those don't actually measure salt, they measure conductivity. And baking soda DOES increase your conductivity, as does any chemical which ionizes when it dissolves.

If you have 'difficult' fill water -- and it sounds like you do -- you may be adding water that's low in actual salt (chloride) but high in measured 'salt' (conductivity). I have no experience or knowledge about operating an SWCG under those conditions, so I can't really tell you what to do. I can guess, bu there may be others who know more.