Its an acrylic so I shouldn't have any problems with silicon. I don't really like them either but It was free... I've been looking at going two ways with actually, both bonsai inspired. One would be a freshwater, with a big hunk of wood covered in java moss, and fast growers in the back. The front would get some anubias, and other misc stuff. Id pump PC's over the top, and DIY CO2 supplementation.
The other one is a bonsai reef tank, but I don't have the funds for another reef aquarium so I might just plumb the hex into my current system and turn it into a display tank type refugium. Lots of algaes, and maybe a spotted mandarin or group of dwarf seahorses. I don't really like brackish fish, They're pretty uninteresting IMO. Id much rather have a large group of tetras so I could see them interact. I was thinking of doing dwarf puffers for a while, but thats passed me.
The only tight thing about hexes is you can do some crazy rockwork-
Heres my clowns too- They're just starting to form a pair, and in the processes of sexing themselves. The females going to be the big one, and the male the one with the teardrop. Hopefully they'll start to breed in the next year or two.