I would recommend pool filter sand which you can pick up at any pool store. It is heavier than play sand and you have less risk of your filter sucking it up and ruining the filter. I just bout 150 lbs. last weekend for my new 135 gallon for under $25. It will be my choice of substrate from here on out , it looks great. I do have a 90 gallon set up with crushed coral in it. But the price of that is over triple. I paid $20 for a 40lb. bag.
