OK, You don't need anything more than LR and LS for bio-filteration. A skimmer rated for 100-150 gallons will remove the waste from the water. Good water movement is key to keeping the waste suspended in the water (powerheads, return pump, spray bars). This is also nessasary for corals to filter feed. A good diverse clean-up crew (snails, crabs, stars, shrimp etc) will take care of the sand/rock. You will also have hitch-hikers (worms,pods) on the LR that will also serve you well for clean up. A sump tank under the main tank will serve as added water to the system providing more dilution of polutents (trate, phos) that will be removed by water changes. 10%-15% WCs will remove nasty stuff and replace trace elements that your critters have used. The sump will house the skimmer, return pump, heaters, this is where your dosing will go and water change duties. Nothing goes directly in the tank but food.
Why do you want to do this? B/C you have no filter floss to change/buy, you have no where for waste to build up and cause problems down the road and honestly its cool to watch all the creatures in your tank take care of your tank.
I have a 55, I use a 15 gal sump, DIY skimmer, 2" LS, 60lbs LR, water movement is about 18x (500 return/spray bars, 3 power heads). I use an old Whisper 60 for carbon and phos-ban when nessasary, usually once a month. I usually steal my wifes new stockings to house carbon/phos-ban in the filter. Lights are 265w PC. I keep shrooms, LPS, star polyps, buttons, xenia, dusters......
Water as of last night was PH 8.2, Trite 0, Ammn 0, trate -5, phos 0, cal 350, alk 10, mag 1300. I use tropic marin salt/ro water and dose nothing. I'm trying kalk to boost my cal.
This is all my own opinion!
HTH
Tim :happyfish