Hi just starting to build up my 120gal reef tank and as my computer has been out of action i have lost touch with you guys.I have my tank in position now but have a question before i put the sand in for my 5" DSB.The company who built my system have positioned my reef flush bar right along the bottom of my tank.They say that i need to put egg crate plastic down then build rocks up on that and only having sand up to the egg crate.Surely sand will slowly fall through under the rocks?They said that i can not build my rocks up on top of the sand as the sand will eventually solidify and cause problems.I would like your advice on this as i will need to raise my reef flush bar so it sits above my dsb if i can build my rocks on top of sand.I can not put any sand in until i know the best way to go.THANKS