@Robin
I use variants of the 5-1-1 mix which is 5 parts fine pine bark, 1 part peat/coir, and 1 part perlite.
Sand in soil is usually useless because it traps water just like peat/coir because it is so fine, except if you want to make the soil heavier. Aloes are very top-heavy so this could prevent it from falling over.
For plants that like to dry out like ficus, philodendrons, ZZ, Sansevieria, Cacti, Jade, etc. I use the 5-1-1 mix. For plants that like it wet all the time I use more peat/coir. Those plants are calathea, ferns, begonias, and so on.
Most indoor plants like to have slightly acidic soil (I believe) which pine bark provides. If you want to raise it, use garden lime.
If you want to dive into soils read this: http://forums2.gardenweb.com/discussions/1378483/taplas-5-1-1-container-mix-in-more-detail
About the ZZ plant: Every plant does better in bigger pots. Sometimes you’ll read that the ZZ plant, sansevieria, Jade whatever ‘likes’ to be in a small pot. All this means is that the plant will tolerate it but won’t thrive. With bigger pots, however, you need to pay attention to the right soil. Peaty soil will retain too much water and drown the plant. With the 5-1-1 mix, however, you can make the pot infinitely big because it does not trap water in between particles but in the particles, making room for air.
If you don’t have a huge number of plants, just get reptibark 2-10mm (bark for reptiles, found at pet stores) which is already the right size, and mix that with perlite and peat. If you have huge containers and many plants, consider sifting. Anyways over at gardenweb you can read yourself to death about soils.
