[mike31154]

Shouldn't be a problem to start the tank with one pump, but in the long term it will definitely benefit from additional flow for reasons already mentioned in previous posts, detritus, rock work, dead spots. You'll need to run the single MP40 at the high end of it's power setting which will be audible for sure. It will also make placement of your softies more of a challenge, to keep them from getting blown around. You'll see that for yourself once you get it up & running.

Once you're ready for more flow, you'd be foolish to not get another VorTech due to the features that allow the pumps to communicate & work together. I have 3 MP40's on my 4 foot 77 gallon Hagen. Started with one new, just before they improved the magnets. Added 2 used MP40s over the course of a couple years to spread the $$ hit. I'm able to run them at a lower speed as a group in EcoSmart Tidal Swell Mode to keep pump sound at a lower level. Also use Night Mode to slow things down, more for sound damping rather than trying to simulate what may happen at night in the ocean.

Have no experience with the new quiet drive pumps, so can't comment on that. I don't find mine that noisy, but there are other things such as air pumps & light fans adding to the ruckus around my tank, so the pump sound is a non issue for me.

I just snagged an MP10 that was on sale. This will replace the MP40 that I have at the center of the back glass. I run that one at an ever lower speed since my Hagen is a narrow tank. The MP10 will suit that position better I think & the footprint will be smaller.