There are alot of substrates you could use. It depends on your setup and how much you want to spend but for a 10 gallon you could use the expensive stuff and still not break the bank. I would use ADA aqua soil, Eco-complete, or Florite. But there are others that with the right setup can work very well. Soilmaster, Turface MVP, pool filter sand, Shultz aquatic soil. Give us more info like... Lighting, Ferts, Co2, and what plants you want and we can better help you.