Substrate

[mbu man]

been looking at a few journals on here of peoples marine aquariums
why do some people not have a substrate?
is their advantages of not having this?

 

[-Nemo-]

Easier to clean without a substrate.
Downside is not being able to keep certain fish/inverts and the bacteria and bugs that usually live there won't be there. Also IMO it doesn't look as nice.