I purchased a Tunze Osmolator Nano 3152 auto top off from Marine Depot less than a year ago. Over the last month or so, some of my coral started to look unhealthy. Most of these have been in my system for years, so I wasn't sure what was going on. I ran all my normal tests - ammonia, nitrite, nitrate, ph, mag, calcium, alkalinity, etc., and everything was still testing normal. I decided to do a thorough cleaning of everything, so I tore out all the equipment and did a large water change. While unhooking everything though, I found what looked like a brown stain down the back side of the sump area in my biocube. Upon looking at it further, I found that the magnet on the ATO float sensor was rusting. All in all, I lost a couple pieces of LPS and two frags of zoas. Not the end of the world, but I would have expected better quality from a reputable manufacturer like Tunze.