Lake sand as in pulling it out of a lake right now or as in sand thats been out of a lake and dried for a period of time?
Live sand is of benifit because it provides a starter bactera bed as well as provides a realistic looking enviorment. In addition quality live sand (not the stuff that comes in bags at the lFS
) will have microcritters in it aswell as the bactera benifits.
'dead' sand can be used as long as its of decent particle size. The smaller the better as far as particles are concerned. In addition the argonite based sand products are good as it can help buffer the PH to some degree. In addition argonite sand is usually much softer as far as the edges vs silica based sand.