Water Pump for 200 gallon tank

Hi all,  I am looking for a water pump that has four qualities

1. quiet, not inaudible, but such that someone could talk comfortably in a room where the pump is operating, also considering soundproofing options.
2. Runs all of the time, this pump will be on at almost all times, however because of this it does not need to be circulating the water terribly fast, just enough to filter all of the water every 12 hours or so.
3. Adds no air to the water when circulation
4. Ideally the fittings would be 3/4 " NPT, but that can be worked around.

So far I have been a little stumped, some aquarium pumps might work because in general they ar ebuilt to be quiet, but what I am looking for in regards to no aspiration and fittings is not readily available as far as I can tell. Pool pumps are similarly frustrating. The few lab pumps I have found have mostly been peristaltic, and I've yet to find any info on how loud those pumps tend to be, I would assume that most of the noise would be coming from the motor? I'm confused, any help would be greatly appreciated.