The water from a softener that uses salts is not ideal because it exchanges sodium for the hard water ions it takes out. These softeners exchange salt of one type (ie calcium, magnesium, sulfer, iron) for a sodium ion. The potassium based salts are less toxic to plants. I've heard of some people using them in planted tanks with no problem. I would just check your GH before a water change, and as long as your plants are not pulling out minerals you're fine. That being said it wouldn't hurt to use the equalibrium to raise your GH in the 5-8 range.