Mine's 6' by 18" with a 2.5" - 3" sand bed. My Melanurus stays mostly to himself but your results may vary. As long as you have a plan if it doesn't work out I'd go for it (if it was me).230; 6 feet by 2 feet. Sand bed is about 3 inches deep except where the engineer gobies have decided to pile it this week.
Wary of the chemical solution because I don't want to kill off the worms.