Hi I just bought a 120 gallon tank and am curious what kind of sand substrate I should buy. I have an amiracle wet dry which is good to 180 gallons and I've heard wet drys are the best for sand. The fish I have are an 8 inch cobra pike, 10 inch tiger oscar, 6 inch green sevrum, and I'm planning on gettin a acarichthys heckelii if I can find someone that's selling a few. I haven't been able to find any.