No one can tell you that w/o some additional knowledge of the type of bark (hardwood or conifer) and size of the particulates (bark, lava/pumice, charcoal ...). You can prolly do w/o anything that will decrease aeration though (sand, cedar shavings, worm castings, almost all the peat or potting soil).

Try reading the link below, and the links at the end of the original post for a container soil overview/conversation.

Al

Here is a link that might be useful: Overview

MM pay attention to tapla.he is the bomb when it comes to dirt.he's the best you'll find re:soil.i have the utmost respect for his knowledge and love of the game.LOL

I am using Al's mix of 1/3 each of turface, screened pine fines, and grit. All my citrus are small (3-10") and in clay pots inside the house. I water 2x a week with
Al's fertilizer mix diluted to about 1/4 strength. This seems to work for me...
With this mix you can water as much as you like. Citrus dont seem to like wet feet but they wont stay wet with this mix due to the porosity.