Product review (2 stars): but it becomes a dark pink like this additive with some added dirt
This makes the humidifier output smell weird. It does seem to keep the filter less calcified from dissolved solids in the water, but I am not sure I want to be breathing the stuff in after all. And when you stop using this, the filter gets to be a very very weird color--not the usual orangey and off white hard water hues, but it becomes a dark pink like this additive with some added dirt.