Planted Tank Guru
Join Date: Sep 2011
Location: Willimantic, CT
Man you're so lucky to have access to all those nice pieces of DW. That "sea monster" setup made me laugh. From your last post I think your first and 2nd layouts are SUPER plain. I like the sea monster setup or the original one you had in your OP. In both of those you can make a cave (glad you were planning on making one anyway!) and have lots of options to scape around and on.
As for derimming the bottom. To be honest I'm afraid of derimming my 10gallons ha! But I have seen many people derim both the top and bottom of the 20L. From what I read you'd wanna absolutely make sure your stand is level so the pressure is applied evenly on the bottom glass. The bottom rim takes the pressure so you're only putting pressure on the outsides of the tank, so removing that makes it kinda dangerous if you're not level. One key thing to remember is if there are cross bracings on the plastic on the top AND bottom black parts, then its not safe to derim. I'm pretty sure your 55 gallon has those bracings?