This maybe a bad idea, but I need a better, cheap"ish" planting medium, and I was thinking playsand. I have a sandbox filled with playsand and I am wondering if I can use that. One thing I am concerned about is tah grain size. Could the it kill my fish and filter? I cleaned the amount I need with a lot of water and some chlorine. Is it useable and if it is, how would I add it to my subtrate?