I have one in the sump for my 180g. A 36 I think. It's very quiet, but does vibrate a bit due to the power. I places a piece of poly filter floss under it to cushion against the acrylic.
I have a 12 that is very quiet, I use it intermittantly to pump water out of my aging barrel. I just purchased a 24 and it sounds like a railroad train going through my Basement. I am still investigating to find out if I have a bad pump, or if they are all that loud.
Dave
I fully agree. 1200 GPh will be roughly 10 times turnover, and there is some loss depnding on head height, so you'll probably fall in the 7X range in reality.
You can get a really good estimate of pump loss due to head height on Aquatic eco-systems website. They have a chart showing flow curves for the mag drive pumps.
Dave