I do. I have a 75 gallon "planted" tank, and I drain it during water changes out the side door, into a little pond where I also take my orchid water from. The water in the pond is combo fish tank water, and also rain water. I have a kind of "orchid superstition" that the de-chlorinator is somehow good for orchids, meaning chlorine or chloramine should not be used on orchid roots. Is this true? I don't know, but it makes sense to me.