The soil that I have been using is made up of the following:

• 60% Perlite
• 10% Earthworm Castings
• 30% Nursery Mix which consists of sand and composted bark fines

I have recently been starting to use a mix of approximately 35% Coir and 65% Perlite as it is very easy to work with and so far has given me good results. However, I have no used it long enough to comment on it. I will write more about this later.

Update

After a number of months with this soil mix, and then with the coir and perlite mix, I have decided to go back to a pumice, pea gravel, and coir mix. I have found that with the addition of perlite (even without the soil being watered) that there is a much higher occurance of orange rot on the roots. While the soil mix with the nursery mix and less perlite did better, it is still not as good as the nursery mix and pumice that I had used previously.

The reason I am now choosing to use coir, is that the addition of the low quality nursery mix (it is the only one I was able to find locally that did not have the addition of peat in it) was showing a lot of fungus and molds in the soil itself and on a number of plants.

So now I am using a mix of approximately:

• 60% washed pumice
• 35% coir
• 5% washed small gravel
  

This mix is getting better responses, and in addition, it is not blown away easily with the fan or with water.