Converting my orchids

[Wrebbitrocks]

ok. so im deciding on switching to either water or s/h culture. any ideas on how to do it. do i just put it into the new culture and wait for the old roots to rot while new ones grow? do i chop all the old roots off and wait for new ones? at what length do new roots have to be to switch?any help is appreciated. oh and in water culture, will any part of the plant rot and die if its beneath the water. a lot of pics show new growths and bottoms of pbulbs completely submerged. wouldnt they rot?