Complex sentence: Table salt may contain added iodine in the form of sodium iodide or potassium iodide, but these compounds will not affect the ion-exchange system, but adding table salt to the dishwasher's water softening unit can damage it.
Split into simpler sentences: Table salt may contain added iodine in the form of sodium iodide or potassium iodide. These compounds will not affect the ion-exchange system, but adding table salt to the dishwasher's water softening unit can damage it.