I set up a ray tank using Leslie's pool filter sand a couple years ago. After a month of cycling, the tank started to leak and the leak was not repairable. I sold the tank to someone for their snake, and I emptied all the sand into my flower bed. After a year, the sand was so sharp, that if I used my hand to dig in the flower bed there, it would scratch my hand all up. Now I am planning to start another ray tank, and there is no way I am using pool filter sand. I know some people do and it has worked out, I am just telling my personal experience that the pool sand wears down and becomes sharp with time.