Soil question

Hi.. I'm just a newbie bonsai hobbyist and I live here in the Philippines. I've read a lot of information on the internet and the one thing that I am having difficulty is getting information on the right type of soil to be used on my medium sized bonsai, specifically "Kalyos." I tried river sands, and combinations of river sands and organic soil plus garden soil.. nothing seemed to work.. please help me on this.. Thanks!

I'm moving this post to Bonsai Questions.

There are several members here from the Philippines and I'm sure they can give you advice on the soils available to you there.