I'm not so concerned about the actual reliability of the unit, or even that is functioning properly, as much as I am about the noise. You can't even hear people talking when in the same room. I recently installed a CPR CS 90 overflow on a 75 gal tank, with an ESHOPPS RS 100 Sump. I know that it could be air in the drain hose, and I have tried adjusting the height of the box inside the DT for the amount of water going into the overflow. I have also tried adjusting the clear pipe/tube inside the box on the back (this is to adjust the amount of air getting into the hose). I have also adjusted the drain hose a little bit that connects to the sump to try a wiggle out air maybe. There are no bends or curves in the hose and there is no point at which the hose would cause the water to travel uphill before it gets to the sump. I also checked the filter sock and sock compartment in the sump for clogs (the sock was empty, just discolored) not sure if that would've helped, but it didn't. I have also just tried removing the black sponge that is over the bulkhead drain in the box, and lowered/raised the internal overflow box in the tank to allow more/less water into the drain.