From my experience, whatever attempts to mix different media of different density and particle sizes would invariably result in a certain amount of separation. I do mix them, but nature reorganises them in her free time

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Snails are aplenty in the garden...from the giant
Achantica (siput babi) to Bradybaena similaris and Subulina sp but they don't seem to be a problem. This could be due to the presence of other lush vegetation that are more palatable than Nepenthes.