Charcoal questions

[jeninhk]

Hey everyone,

I have been slowly rescuing many orchids given to me that i now realize have been poorly neglected and "abused" by the previous "orchid collector" (some have even been potted in soil!) anyways I am trying to teach myself about orchids in my attempt...

I have noticed repotting some of the plants she did put some charcoal.. and when i went to the nursery to get repotting supplies the man with poor english helping me (i am in Hong Kong) mentioned charcoal but could not explain to me what to use it for and why.

My questions are.. is charcoal essential? what does it do? I was planning on repotting using orchid rocks and bark mixed together.. should i mix charcoal in with that?
and can you reuse charcoal from the old pots?


thanks everyone!