those bottled ones will propagate if given the right tank parameters. those pods reproduce like wild fire. its like having sex w/o a condom man using someone elses chaeto and throwing it in ur tank. u may or may not get burned but y take a risk?If you get it from someones macro then you know it grows well in a home tank. When you get it in a bottle it may not propagate (but most likely will). But yes there is a chance of picking up something you don't want.