i bought a packet of potting clay. the bag says the clay contains minerals suitable for plant growth. can i use potting clay? i read about using only distilled water to water the VFT as tap water contains minerals that will kill the VFTs.if so will the minerals in potting clay kill the VFTs? also can alkaline soil be used to pot VFTs or only acidic soil is allowed, coz i am not sure if the potting clay mix is alkaline or acidic.