The ex vacations in Florida and leaves my kid with people that smoke pot, what can I do?

When a child has two parents who differ on issues, in some ways she is getting a broader education in life. She will be able to understand that issues are not black and white, observe the effects, negative or positive, of pot smoking and many other things that you and your ex don’t agree on and be richer for it. You can’t control her life when she is not with you so just concern yourself with being the best person you can be and modelling the best example you can while she is with you. Don’t take this opportunity to criticise your ex in front of your daughter either, because that is vitriol that will be a very bad influence on her (much worse than being in the presence of pot smoking!). Relax, let this go, because it is not a huge affair (despite your seemingly rigid stance) and save your intervention, if it is ever needed, for something more important.