Well let me put it this way better be safe then sorry!5 years ago,i lost a Chamaeleo Calyptratus because of impaction disease,to prevent your chameleon from eating the soil and contracting impaction disease(serious problem)are other types of problems like parasites for exemple platyhelminthes(cestodes and taenias)the eggs of these parasites are usually ingested when the mouth or tongue of the feeding chameleon come into contact with infested soils.First i change my soil 3 to 4 times a year(organic soil) then i put screen on top of the soil and i put river rocks on top of the screen,use river rocks big enough to prevent your chameleon from acidently swalow them.It looks nice,it s easy to clean and keeps your chameleon safe.