@reefinatl Not only have I been doing it to set up new tanks to allow me to add corals almost immediately for ~25 years but also when I called in to deal with nuisance algae issues it's about the only thing I'll do besides manual removal. Are there tanks that would not be advisable to use, certainly. But what I realized a long, long time ago was there's a lot of beneficial stuff besides just nitrifying bacteria in a system. We know now most of the microbial stuff on reefs can't be cultured let alone stuck in a bottle. It's well documented DOC corals release help promote beneficial autotrophic processes. Why wait until corals are established and are promoting these processes when homeopathic water from a "healthy" system can be added to help establish these beneficial processes.
have you checked to see if there are any fish forums local to your area? some have a pay if forward section (at least mine does) where if you're kind, people are more than willing to give you some free corals.
Also would it be a Horrible idea to get a piece of wood with barnacles and stuff soaked in saltwater and add it to mimick trash thrown into the ocean or would it be safe. I see tons of it when I go to Florida