Did mine today so thought I would post a few pics and advice for any more of you doing this to their Red Sea Max 130D.
I used 2 x Fractal Design 50mm Cooling fans rated at 20dB. The good thing about these fans is that they have a nice long lead and a braided sleeve to protect and help route the cables.
IMAG0988 by
David FXS, on Flickr
As most have found, the 50mm computer fans are slightly to big and need to be thinned down slightly. If you push them in as they are they will be noisy as the fan casing is being squashed. I thinned them down this using a flat file on a table and gently sanding the fan back and forth over the file.
IMAG0990_BURST002 by
David FXS, on Flickr
You can see how much material I removed on the left to get them to fit well.
IMAG0992 by
David FXS, on Flickr
As the leads were long enough I did not need to splice into the existing fan cables and could wire the Red and Black cables directly into the 12V connector block on the board and cut of the Yellow.
IMAG0993 by
David FXS, on Flickr
IMAG0996 by
David FXS, on Flickr
Another shot of the cable routing and also you can see the existing loom still encase you ever want to return to stock.
IMAG0998 by
David FXS, on Flickr
Initially on Start up I didn't think they had made much difference in the quiet room with the pumps off. Now tonight with all the normal family life around, I actually can't hear the tank and I'm over the moon with the improvement.