Good cactus soil mixture?

These are my first cacti in a while. I made a dish garden with a 12 inch plate usually used under a container for water. What I did is I mixed about 1 part old horse manure (only soil I had) with about 2 or 3 parts creek gravel. I have a creek behind my house and the gravel is small so I thought it would act like sand. Additionally I added a layer of medium to large gravel on the bottom (from my driveway I think it's limestone. I used it before). Does this sound good? Thnx.