Most people have told me that I should shoot for between 10 and 20 times turn over for my new reef tank. My question is, is this 10-20 times DT volume or total volume.

I don't know if it is right but I use DT.

Yea i use DT here too, Think about it this way for the most part you are wanting to move around local flow for the corals and to keep the water moving. If it was the TWV then you would be pushing around water that isn't there. Does that make since? Thats how i have always thought about it anyways.

my DT is about 32x turnover of 100gal. (seio 1500, Mag18 Closed loop, and various PH's), and my TWV is about 39x turnover (with mag9.5 return added, give or take a few GPH with head loss).

it should be of the display tank, NOT of the total water volume

also note there is a different in turnover and in current.
you want 10-20x in current, not really in turn over.

turnover includes water that leaves your system and goes to your sump, then back up, but does NOT include anything contributed by power heads, skimmers, or closed loop systems.
current includes everything in a tank that moves water.

the two can be very different and may need to be set very different, for example you may have a display tank that need about 25x in current, with a refugium attached. obviously for the fuge to work well you want to keep the flow low.
so you will have a display with 25x current but only 8x turnover *8x is what foes to the fuge)

Thanks everyone your answers are much appreciated. So if I plan on around 17 times my DT volume in current, through powerheads and 10 times turn over in my sump/fuge does this sound like a pretty good baseline to get started. The display is a 75g and I have a 20g sump and a 29g fuge.