Thanks! At first I thought it was the first one, but then I ran a tape measure from the base to the ring clamp for the MPV, and it looked to be close to 23". Would that be how I'd measure it? If so, thanks for helping to verify my suspicions.
That beast ran on an 18x48 for the past couple years. I know its A WHOLE LOT, but it was free. I just think I could have ran my filter a lot less. I only found this site a couple weeks ago, and just ran the thing 24/7. I've probably wasted like hundreds in electric bills over the past couple years.
Again, Thanks!