I asked about this recently on another thread, and Iratherfly said that the charcoal tablets/capsules would be fine. Buy at any chemist. He suggests mixing the charcoal with the salt in the proportion of 5:1 (ie if you are going to sprinkle your cheese with 5 gm salt, then add 1g charcoal. I gather the PC/Geo grows over the charcoal coating, which is why you can't see it until you cut the cheese. This is theoretical on my part, still on my to-do list. However, I do have a bottle of 250mg charcoal tablets, and according to the label the tablets contain sucrose and lactose (but in unspecified amounts), so I reckon about half a tablet would be about right for that amount of salt. Bashed up of course. Using a tea strainer seems like a good idea.