Hello, I have some 'sand' in my fluidzed bed filter that came out and oto my substrate, I used some of this for my other planted tanks, would you guys know the name of this sand it's very fine, is it 'silica sand' and where would I be able to purchase it? i believe it's used for reptiles also? etc thanks Raymond Wong http://ww.sfu.ca/~rww/Aquariumstart.htm