I'm old fashioned so I use clay mixed with vermiculite packed about 1 in. in the bottom and then cover this with fine gravel or a thin layer of sand. Don't do this if you have fish that like to dig or plough. Real cheap! If you are afraid of diseases you can bake the substrate. Joe --------------- See http://www.aka.org/AKA/subkillietalk.html to unsubscribe Join the AKA at http://www.aka.org/AKA/Applic.htm