First thing I realized when getting ready to do Rockwork in the 400 was that it was not easy climbing in and out of my tank so I went and had a 3/4 piece of Melamine cut the size of my tank interior, 98.5" x 34.5". I also added the bulkheads in the bottom for my closed loop and made sure the measurments were perfect so the rocks I would build would set on the existing plumbing. I used Rocks I have been collecting for 3 years along with a Arch that is Ceramic made by Aqua-Tecture that I picked up at RAP. I want a very minimal look with hiding my closed loop plumbing my main focus. Enjoy and let me know what you think.