Hey Rishma: if you look back a few pages, I did a review on the VarioS-4. My criteria is absolutely silence. I could care less if it used more power than other pumps, or looked uglier, as long as it performs how I need and is silent, I'm happy. And I am. The VarioS-4 is incredible. Ambient sound reads 46 decibels, with my VarioS-4 at 70% power (using Apex VDM to control it), the decibels do not increase, even in the cabinet. I have a VarioS-2 that powers my reactors/chiller that's running at 75%, and that one also leads to 0 increase in decibels. The float switches are a great safety feature, and the fine tuning ability with a simple connection to a VDM is fantastic. I have yet to have any issues! I purchased an extra VarioS-4 on black friday as a backup just in case, though not sure if I'll ever need it. I purchased the VarioS over the Ecotech, simply because at the time the S1 didn't exist yet, and the M1 was a really tight fit. I didn't think I'd care about Apex control or the float switch, but now that I have them, it's such a great perk. Can't say enough good things. I wish my skimmer was quieter (it's the only thing that makes any noise in my system). I wanted a Reef Octopus Elite SSS, but there isn't one small enough for the tank. I bet that thing is silent too.