Is this a bad idea?

[Aquattro]

Originally Posted by PoonTang

also FWIW everything I have read suggests that transferring over your old water will do nothing to help out the cycle but it will help acclimate the fish a little better.

Agreed. Bacterial content is insignificant, but chemistry could make transition for the fish easier. I prefer to start with all new water though, as I'm switching salt between tanks.