I had a old Tunze Osmollator that finally gave up the ghost after years of faithful service - it would top off the sump every day or two. I replaced it with a new 3155 and instead of doing a major refill every day or so, it turns on for 20 - 30 seconds to do a micro-top off every 10 minutes which is driving me crazy? Do I have a defective water sensor or is it supposed to do that? If it is supposed to do that, how do I get it to stop? As an FYI, it doesn't overfill the sump, it is just way too sensitive for my liking. Thx in advance for your help/advice.