IMHO, most of us were "educated" about CPs from books and sources originated from western countries such as US and Europe. Over there, especially in North America, the water source is usually "hard" water hence containing high amount of dissolved minerals (high KH) such as calcium and etc.
As far as I know, most natural water source found in Malaysia is usually consider as "soft" water. The point is, IMHO, if you grow your neps outdoor, regular tropical rain will flush away excess mineral hence depleting the potting media of any trace of nutrient/mineral (if there's any in the first place)...
However, many of us (me included
) have even apply fertilizers to the foilage and into media (once or twice of month). I even add slow release fertilizers (Osmocote -6 months- 14-14-14) when ever I repot my neps. So I think all the worries about excess mineral that might cause harm to neps is probably a misconception from the knowledge pass down to us that originated from US / Europe long time ago. FYI, Fauzi use regular tap water to water his neps everyday and Lim use untreated well water (underground water) to water all his CPs including Droseras, Sarras and etc... Interesting fact isn't it??
My 2 tiny cents....
