hi i have a 12gal nano dx.i did not install the bio-balls or the ceramic rings i left all 3 sponge filters in place.the tank has been running for about 2 1/2 months.i have a 3/4 inch live sand base and live rock.i do not have any live rock in the filter compartments.i only did 1 water change so far but i did add some fresh and saltwater to the tank to make up for evaporation and adjust the salinty.i had some small life within 1 week of setup.i now have stomatella snails,many isopods,bristleworms,a good population of pinapple sponges,white flatworms,5 or 6 small snails i cannot identify and a new piece of rock i purchased about 1 1/2 weeks ago that has some discosoma/mushroom polyps.all is doing well.now to get to the point this is my first salt/reef tank i think you should not let it become to complicated take your time and do some research follow the rules but dont become a sheep.also the recent addition of live rock i purchased came with some cool hitchhickers some small tubeworms a spaghetti worm some nice algae and sponges.i am adding a colony of zoanthid and xenia this weekend then i will let the tank chill for a while before any new additions.good luck go slow and have fun i love this stuff to cool.