i have just got a 2yr old bearded dragon. he came with his own viv.i have looked all over the net and eveyone says dont use sand dont use bark dont use this or that.what is the best to use.the viv he came with has bark in it and he is in perfect condition.if i change it will it upset him as he is use to bark.is sand ok or not please help i seem to be going round in circles with this one