I had a bare bottom for a month or so, and decided to add a thin layer of sand. Just couldnt get used to the look of no substrate. Just my personal choice! Try bare bottom and if its not for you just add sand later. On the filter side, Im running an external filter with just ceramic rings, this also feeds my uv steriliser! trickle filter with bio balls, and carbon and phosphate remover in the sump. Ive removed all sponge filters from the system and use floss as a pre filter before the trickle, takes out fine particles and easy to clean/replace. Skimmer is essential, ive got a DELTEC MCE300, awesome piece of kit! All works fine for my 280ltr fish only system. Hope this helps.