Deep Sand Beds
A good article on DSBs. A sea cuke will be excellent and is on my list for the next critter addition. My DSB is 4-5 inches. Move your LR off your DSB as burrowing critters will cause avalanches. Possibly consider a horseshoe crab. They stir up a lot, and are quite interesting. Sand sifting star is good. Get some cerith and nasarrius snails and possible a conch...they will all help with sand stirring and yes, you will need these creatures to keep gas from building up.