I like it! Whats the white piece between the spray bar and the outlet of the eheim? Personally I just cut a one inch piece of tubing to fit the spraybar to the outlet.
One thing: If you place the AC filter (or whatever HOB filter you got there ) on the left and the eheim on the right you wont have any intake tubes in the middle part of the tank, only on the edges of the tank. Gives a more natural look IMO
lace rock typically comes out of utah. a lot of the decent landscaping places will have pictures of it online and all that. (price runs about 7$ per ton) and im sure they get calls for fish tanks often. so the idea is maybe search for a nice store that may ship u say 70 lbs worth in a box.(USPS Flat-rate shipping) its worth a shot since it is so hard to find online. all my LFS carry it so i just pick up single peices as i find them.