A medium's ability to work when wick watering is employed depends in very large [part on the size of the soil particles, which is what drives it's ability to pull water upward (capillarity). If you're using a wicking system with enough capillarity for the system to work, it's highly likely the medium is not well-suited to growing succulents.
Example: Both the following media are well-suited to growing succulents because of their high porosity and reduced ability to hold excess (perched) water.
Unfortunately, because of their limited capillarity, they are not good candidates for wick watering. You could use a wick with a high degree of efficacy to DRAIN excess water from pots, but not to pull water up from a reservoir into the medium.
You can easily prevent mold and other forms of unwanted growth in reservoirs through use of a UV light and/or by adding H2O2 (hydrogen peroxide) to the water in the reservoir. H2O2 is a powerful oxidase because of the O- free oxygen radicals it contains, and will attack the first organic molecule it comes in contact with.
Al
