Product review (4 stars): I need this bacteriostat stat!
We've been adding a capful of this to each tank-filling of our Essick Air MA1201 Whole-House Humidifier this winter.  We haven't had any mildew or bacteria or slime in the humidifier, so I'm guessing the bacteriostat is doing the trick.  The price seems a bit high, but it looks like one bottle will last us the entire season (so a whole year really), so maybe it's a good deal after all.  It doesn't smell and is easy to use, so I like it!