JUNK!
Back in the day the Quiet Ones were a pretty good pump butthe ysuck today. I had a 4000 literally burn up, flames, sparks and all on my 100G mixed reef. I stuck my hand in the tank and it was hot to the touch and I felt a tingle.
I thought it was a fluke so while waiting on a replacement, out of warranty of course, I used my Ocean Runner 3500 spare. The tank temp dropped 3 degrees, the tank was quieter and my power consumption dropped 13 watts while the flow increased. I reinstalled the new 4000 and the temp went back up anhe power went back up. I also found with both the old an new that they had trouble restarting in a power outage. It went in the trash.
I also had a Quiet One on my calcium reactor as a recirc pump. One day I opened my stand to add water to the sump and was squirted by water! Turns out the motor housing cavitated or developed a hole right through the mte windings and was filling my stand with water.
I wouldn't wish a Quiet One on my worst enemy. They did not acknowledge me when I contacted them and their pumps are garbage.
I would suggest a Water Blaster, Eheim, Octopus or Ocean Runner if you want a constant speed AC pump or look at some of the new DC pumps that are variable speed/flow.
I did a big write up some years ago for Reef Central back when I was part of Team RC on pumps and tested many of them available at the time for heat gain, power consumption, ability to ump against head and noise using a dB meter and Quiet One and Mag were low on the list.