The new one does not run the pump on start up, it flashes a light until it is active which is primarily the time needed for the thermal back up to heat up and register a default temperature. I am overall very impressed with the new version and I have used the Osmolator for over 20 years, since the 3150 which used two floats. It is a big advance but I generally would not upgrade until you need to, the 3155 works very well, the main thing this adds is it is waterproof and a much cleaner unit without a lot of wires. I know first hand it is pretty thoroughly tested, it has been in development for years, with many, many revisions as we know, we can't make a mistake on this product. The safety sensor in particular, almost every technology was tested from capacitive touch, to micro floats, to conductivity, to pressure sensors and they all failed in testing and this thermal system is very carefully designed and tested. I have tried messing it up, hot water, cold water, salt crust, all the things that messed up the other options don't phase it and if it detects an unusual operating condition, it just refuses to run.
Great on Paper—but Would You Trust It With Your Reef?
