I don't know what the composition of Mineral Mud is, but I think its value for plants (assuming it has any) would be from inorganic nutrients - potassium, iron, magnesium - that are less present in typical aragonite sand. Adding detritus should increase the organic nutrients available in the sandbed. Adding detritus and sand from other tanks should help a new, relatively sterile sandbed start aerobic and anaerobic bacterial processes. You may also bring in some bugs and worms that way. Personally, I'd invest in live sand from long-established vendors that have used sandbeds as part of their culture systems for many years to bring in a better diversity of bugs, worms, and micro-molluscs. Two I've used and recommend are
Inland Aquatics (IA -Indiana)and
Indo-Pacific Sea Farms (IPSF - Hawaii).