im upgrading to a 125 from my current 55. its going to house my current oscar, clown knife, palmas, and Jack Dempsey. I want to use a lot of sand and driftwood but buying aquariums sand will be hundreds of dollars. can i just use steralized childrens play sand? its $2.50 for a 50 lb bag and its what i use in all of my reptile tanks. i wanted to go with a natural color anyway. anyone use this in the past? is there anything in it that would kill my fish?